Datasets:

olivierdehaene

/

xkcd

like 6

Christmas GPS

Christmas GPS

https://www.xkcd.com/201

https://www.explainxkcd.com/wiki/index.php/201:_Christmas_GPS

Cueball: Check it out - I got a GPS receiver for Christmas! What should we do with it? Megan: Let's take our latitude & longitude, put our birthdays after the decimal points, then go to that spot and make out. [Cueball is in love.] Merry Christmas from XKCD [ sic ] [Car driving off in to the distance.]

In the comic, Cueball has gotten a GPS device and asks Megan what to do with it. She suggest that they take their current coordinates and modify the latitude and longitude with a simple function based on their birthdays, thereby pointing to an arbitrary, non-random location. For example, if Cueball was born on, let's say, April 1, 1986 and Megan on August 12, 1988 and they are somewhere in New York ( 40.768062,-73.98468 ), the coordinate they type could make ( 40.040186, -73.081288 ) (assuming US date format), or ( 40.860401, -73.880812 ) (assuming following ISO 8601 ). The good thing about keeping the number before the decimal point is that the distance is still realistic to get to by car. Megan suggests to make out in this place. This procedure is somewhat of a precursor to Geohashing . The comic is a Christmas comic, since it came online on Christmas Day 2006. The title text suggests that if the location you make for yourselves is over water (which the example above happens to be), you either need to find a boat or find some rule that you can change to preserve the promise of making out, and if you can't do either, then there is no way you'd get to make out. Cueball: Check it out - I got a GPS receiver for Christmas! What should we do with it? Megan: Let's take our latitude & longitude, put our birthdays after the decimal points, then go to that spot and make out. [Cueball is in love.] Merry Christmas from XKCD [ sic ] [Car driving off in to the distance.]

YouTube

YouTube

https://www.xkcd.com/202

https://www.explainxkcd.com/wiki/index.php/202:_YouTube

[Caption above the panel:] The Internet has always had loud dumb people, but I've never seen anything quite as bad as the people who comment on YouTube videos. [Below shows a still of a 44-second video of Moon landing. An astronaut is seen at the center of the still with an Apollo lunar lander at the background.] [Below the video shows a list of comments, top to bottom:] Comments & Responses [The name of the commenters and the time when the comment was posted is shown above each comment in a gray background.] rocckir (48 minutes ago) this is so obviously faked its unbilevable, why r people so gullible??? morons (reply) (mark as spam) bigmike133 (35 minutes ago) ive seen the space shuttle ass hole it definetly landed on the moon do some research... (reply) (mark as spam) GunPistolMan (22 minutes ago) if it was real why is their gravity? americans r fucken sheep (reply) (mark as spam) crackmonkey74 (17 minutes ago) u dont think we went to the moon why not tell louis armstrong to his face (reply) (mark as spam) simpleplan2009 (5 minutes ago) it was a soundstage on mars (reply) (mark as spam) In July 2009, a restored video showing Neil Armstrong's first moonwalk was uploaded to YouTube. User Michael Huang copied to that video's comments section all the sentences in this comic. Then, after some other users took some of his comments seriously, he later added another comment stating, "This entire comment chain is from the famous webcomic, xkcd." The comments are copied verbatim, including typos and grammar errors. The only mistake is in the first comment: Michael Huang included only one question mark when the comic has three of them.

This comic is pointing out the fact that many of the comments on YouTube videos are insipid and poorly informed, being pointless arguments over some minor topic or factually incorrect position ( conspiracy ). At the time of this comic, YouTube was fairly new, and the comic's observation about the inanity of YouTube comments was novel. Since then, this observation has become a widely accepted truism about the Internet. In this case, the Moon landing hoaxers are at the receiving end of Randall 's pen. The reputation of YouTube comment threads as cesspools of abject stupidity and blatant trolling is revisited in 301: Limerick and 481: Listen to Yourself . The username CrackMonkey74 appears again in 406: Venting and 574: Swine Flu . The title text is the first reference to Sheeple , which appeared a few more times in xkcd comics. [Caption above the panel:] The Internet has always had loud dumb people, but I've never seen anything quite as bad as the people who comment on YouTube videos. [Below shows a still of a 44-second video of Moon landing. An astronaut is seen at the center of the still with an Apollo lunar lander at the background.] [Below the video shows a list of comments, top to bottom:] Comments & Responses [The name of the commenters and the time when the comment was posted is shown above each comment in a gray background.] rocckir (48 minutes ago) this is so obviously faked its unbilevable, why r people so gullible??? morons (reply) (mark as spam) bigmike133 (35 minutes ago) ive seen the space shuttle ass hole it definetly landed on the moon do some research... (reply) (mark as spam) GunPistolMan (22 minutes ago) if it was real why is their gravity? americans r fucken sheep (reply) (mark as spam) crackmonkey74 (17 minutes ago) u dont think we went to the moon why not tell louis armstrong to his face (reply) (mark as spam) simpleplan2009 (5 minutes ago) it was a soundstage on mars (reply) (mark as spam) In July 2009, a restored video showing Neil Armstrong's first moonwalk was uploaded to YouTube. User Michael Huang copied to that video's comments section all the sentences in this comic. Then, after some other users took some of his comments seriously, he later added another comment stating, "This entire comment chain is from the famous webcomic, xkcd." The comments are copied verbatim, including typos and grammar errors. The only mistake is in the first comment: Michael Huang included only one question mark when the comic has three of them.

Hallucinations

Hallucinations

https://www.xkcd.com/203

https://www.explainxkcd.com/wiki/index.php/203:_Hallucinations

[Two Cueball-like guys are talking. Above them is the following caption:] Sometimes it seems bizarre to me that we take dreaming in stride. Friend: Are you coming to dinner? Cueball: Yeah, but first I'm gonna go comatose for a few hours, hallucinate vividly, and then maybe suffer amnesia about the whole experience. Friend: Okay, Cool.

Cueball on the right is talking to his (Cueball-like) friend about dreaming but using words and phrases to make dreaming sound much more dramatic than we usually think that it is. However, the description is technically correct. Randall is using the comic to make a point about how we think dreaming is so normal, but if we actually realize what's happening, dreaming is very strange: The character on the left takes this as though the experience is normal. Which it indeed is, but that is why Randall has the caption above the guys: Sometimes it seems bizarre to me that we take dreaming in stride. The title text is about lucid dreaming , where the dreamer is aware that they are dreaming. This is even more fascinating to Randall. He uses this type of dream in 269: TCMP . [Two Cueball-like guys are talking. Above them is the following caption:] Sometimes it seems bizarre to me that we take dreaming in stride. Friend: Are you coming to dinner? Cueball: Yeah, but first I'm gonna go comatose for a few hours, hallucinate vividly, and then maybe suffer amnesia about the whole experience. Friend: Okay, Cool.

America

America

https://www.xkcd.com/204

https://www.explainxkcd.com/wiki/index.php/204:_America

[A timeline with only three ticks with years noted. Each tick is labeled with a line going to the tick. The second tick is much closer to the last on the right and has its year written below the line. The other two have it above the line and vice versa with the labels. Below in the middle there is a caption.] 1776 Declaration of independence 1979 Jimmy Carter attacked by giant swimming rabbit. 2007 Present day [Caption:] America must never forget.

On April 20, 1979, U.S. President Jimmy Carter was allegedly " attacked by a giant swimming rabbit " while solo-fishing on a boat in his hometown. The reality is a little more nuanced: According to Carter, the rabbit had actually been chased into the water by some hounds and swam near his boat. Carter splashed some water on it to compel the rabbit not to come any closer. Nevertheless, the newspapers ate it up, reveling in the ridiculous notion that anyone would feel threatened by a rabbit (considered by some to be small, harmless herbivores [ citation needed ] ), with respected paper The Washington Post putting the story "President Attacked by Rabbit" on the front page. Since the White House refused to release the photograph, the paper created a cartoon parody of the rabbit, calling it PAWS, in reference to the blockbuster film JAWS , about a killer shark. Carter's opponents used it as fodder for their arguments that Carter's presidency was weak and ineffectual, and basically, the whole thing was blown way out of proportion by the American media, as so often happens with goofy events such as this. This comic treats the Killer Rabbit attack as a dark day for the United States and uses the phrase "America Must Never Forget," which usually applies to days like the Pearl Harbor attack or 9/11 . It essentially claims that, for the entire history of the United States (which starts with the signing of the Declaration of Independence ), it is the only event worth remembering. The rabbit incident is also referenced in 1688: Map Age Guide and in 2086: History Department . The title text is an assumption that the event has not been remembered in the way the comic jokes that it should have been, and as a result, younger readers will think he is kidding when he says Carter was attacked by a rabbit. [A timeline with only three ticks with years noted. Each tick is labeled with a line going to the tick. The second tick is much closer to the last on the right and has its year written below the line. The other two have it above the line and vice versa with the labels. Below in the middle there is a caption.] 1776 Declaration of independence 1979 Jimmy Carter attacked by giant swimming rabbit. 2007 Present day [Caption:] America must never forget.

Candy Button Paper

Candy Button Paper

https://www.xkcd.com/205

https://www.explainxkcd.com/wiki/index.php/205:_Candy_Button_Paper

When it came to eating strips of candy buttons, there were two main strategies. Some kids carefully removed each bead, checking closely for paper residue before eating. [To the right, a small section of a strip of Candy Buttons paper is shown. Two red buttons have been removed from the top of the strip.] [To the left, a long strip is shown. It seems to be waving in the air.] Others tore the candy off haphazardly, swallowing large scraps of paper as they ate. Then there were the lonely few of us who moved back and forth on the strip, eating rows of beads here and there, pretending we were Turing machines. [A strip is shown from bird's eye view. Many rows of buttons have already been eaten.]

This comic refers to Candy Buttons , a type of candy sold by Necco in the U.S. since 1980. Because they were glued to paper, each candy button would have some paper stuck to it. As said in the comic, some kids would carefully check each candy button to make sure they would not accidentally eat paper, while some kids didn't care and ripped them off, eating large scraps of paper in the process. Because of the resemblance of the strips of paper to the tape of a Turing Machine , a small minority of children (possibly only Randall or some of his friends) pretended to be a Turing Machine by creating rules and executing them upon the tape of candy exactly like a real Turing Machine would do. The title text refers to the fact that, although it would be hypothetically possible to create a Turing Machine that can only delete symbols, the information density of the tape would be greatly reduced, and the original Turing Machine could read and write from the tape it operated on. When it came to eating strips of candy buttons, there were two main strategies. Some kids carefully removed each bead, checking closely for paper residue before eating. [To the right, a small section of a strip of Candy Buttons paper is shown. Two red buttons have been removed from the top of the strip.] [To the left, a long strip is shown. It seems to be waving in the air.] Others tore the candy off haphazardly, swallowing large scraps of paper as they ate. Then there were the lonely few of us who moved back and forth on the strip, eating rows of beads here and there, pretending we were Turing machines. [A strip is shown from bird's eye view. Many rows of buttons have already been eaten.]

Reno Rhymes

Reno Rhymes

https://www.xkcd.com/206

https://www.explainxkcd.com/wiki/index.php/206:_Reno_Rhymes

[Cueball and Black Hat stand facing one another. Black Hat is on the left.] Black Hat: You know, I once shot a man in Reno, just to watch him die. Cueball: Really? Well, I once shot a man in Reno, but I couldn't tell you why. Black Hat: I once shot a man in Reno, then I went home to cry. Cueball: I once shot a man in Reno, then I watered his cacti. Black Hat: I once shot a man in Reno 'cause they cancelled Firefly. Cueball: I once shot a man in Reno, him and all his succubi. Black Hat: I once shot a man in Reno and a bunch more in My Lai. Cueball: I think we're done.

This comic starts with a line from the song "Folsom Prison Blues" by Johnny Cash. Cash is noted as saying, "I sat with my pen in my hand, trying to think up the worst reason a person could have for killing another person, and that's what came to mind," which fits pretty well with the personality of Black Hat . Rather than react badly, Cueball starts a rhyming game, which they continue until Black Hat refers to the horrifying My Lai Massacre , which is apparently going too far for Cueball. You know, I once shot a man in Reno, just to watch him die. Black Hat starts with the original line from the song. Really? Well I once shot a man in Reno but I couldn't tell you why. Cueball then begins the rhyming game by saying that he can't tell the reason why he killed the man. I once shot a man in Reno then I went home to cry. Black Hat continues by saying that he got emotional after killing the man... Unlikely, given that he's Black Hat , and it could be him trying to continue, or he could be being sarcastic. I once shot a man in Reno then I watered his cacti. An unlikely action after you have just killed someone, unless you're elaborately trying to cover up your actions. More likely, Cueball is just trying to continue the rhyme. I once shot a man in Reno 'cause they cancelled Firefly. Firefly was a TV series that aired on Fox during 2002. Its cancellation was a source of much annoyance to its fans, a fact frequently referenced in xkcd. In this case, Black Hat goes as far as to murder someone for this. I once shot a man in Reno, him and all his succubi. Cueball says he shot a man and a bunch of female demons. Unlikely to happen in real life, and is just probably Cueball attempting to continue. I once shot a man in Reno and a bunch more in My Lai. The My Lai Massacre was an atrocity committed by US soldiers in Vietnam during the Vietnam war. Here, Black Hat says he not only shot a man in Reno, he shot a bunch more in My Lai , meaning that he was actually part of the massacre. Cueball is obviously horrified by this, and he ends the rhyme with a "I think we're done," signifying his horror at Black Hat's words. The title text continues the rhyme, but changes the roles: now the speaker is asking someone else if they shot a man in Reno. It may be a reference to The Princess Bride (Inigo says the "I don't mean to pry" part to Westley). [Cueball and Black Hat stand facing one another. Black Hat is on the left.] Black Hat: You know, I once shot a man in Reno, just to watch him die. Cueball: Really? Well, I once shot a man in Reno, but I couldn't tell you why. Black Hat: I once shot a man in Reno, then I went home to cry. Cueball: I once shot a man in Reno, then I watered his cacti. Black Hat: I once shot a man in Reno 'cause they cancelled Firefly. Cueball: I once shot a man in Reno, him and all his succubi. Black Hat: I once shot a man in Reno and a bunch more in My Lai. Cueball: I think we're done.

What xkcd Means

What xkcd Means

https://www.xkcd.com/207

https://www.explainxkcd.com/wiki/index.php/207:_What_xkcd_Means

[Caption above the panels:] What does xkcd mean? [Two cars sitting at a red light at a multi-lane intersection; one of them makes a right turn, then shifts over to the left lane and makes a U-turn across the dividing line to go back the way it came. It then shifts back to the right lane and makes another right turn, continuing down the road past the traffic light. This is shown with a red arrow.] It means saving a few seconds at a long red light via elaborate and questionably legal maneuvers. [In an inset circle in the panel, someone is on a cell phone. In the panel itself, a second person is looking at a dog.] It means having someone call your cell phone to figure out where it is. Dog's stomach: Ring [The mathematical function "A(g 64 , g 64 )=" appears in the panel. Next to the equal sign stands a mathematician, clutching his head.] It means calling the Ackermann function with Graham's number as the arguments just to horrify mathematicians. Mathematician: Aughhh [An approximately 8 by 8 square of floor tiles is shown; the first, fourth, and seventh across in the first, fourth, and seventh rows are black, and the rest are white. A guy and girl are shown next to it, walking on what is presumed to be the same pattern of floor tiles.] It means instinctively constructing rules for which floor tiles it's okay to step on and then walking funny ever after. [Line indicating the uppermost right black tile: Black tiles okay.] [Line indicating tile directly below it: White tiles directly between black tiles okay.] [Line indicating a white tile in the last column over: Not okay.]

This comic purports to finally answer the question, " What does 'xkcd' mean? " However, instead of giving an answer as to what the letters actually mean (according to Randall, it's literally "just a word with no phonetic pronunciation"), he offers five quirky behaviors. This is reminiscent of TV commercials that ask, "What does [brand name] mean? It means [happy activity]!". The first panel shows a driver, marked by a red line, making a right turn at a red light , a U-turn on the connecting road, and then another right turn, returning them to their original direction presumably faster than waiting for the light. Right turns at red lights and U-turns are legal in all 50 states, but some intersections do not allow them (and turning at a red light is illegal everywhere in Europe). Hence, this complicated maneuver is "questionably legal". However, under certain circumstances in the US state of Oregon, it appears that this is actually legal . The second panel shows Cueball searching for his mobile phone by having his friend call it to locate the ringtone, only to hear a ring from inside of his dog's stomach, possibly a reference to Jurassic Park III . In the third panel, Graham's number is a (very) large number (once celebrated as the largest number ever used in a proof, although it is no longer the record holder), and the Ackermann function is a (very) fast-growing function, thus the function's output must be insanely large. (In fact, A(g 64 , g 64 ) is actually smaller than g 65 .) The fourth panel shows somebody walking in a pattern based on the position of black and white tiles on the floor. This is further referenced in 245: Floor Tiles . The title text refers to stigmata , marks corresponding to Jesus' crucifixion wounds. Devout Catholics have claimed to have spontaneously developed stigmata. [Caption above the panels:] What does xkcd mean? [Two cars sitting at a red light at a multi-lane intersection; one of them makes a right turn, then shifts over to the left lane and makes a U-turn across the dividing line to go back the way it came. It then shifts back to the right lane and makes another right turn, continuing down the road past the traffic light. This is shown with a red arrow.] It means saving a few seconds at a long red light via elaborate and questionably legal maneuvers. [In an inset circle in the panel, someone is on a cell phone. In the panel itself, a second person is looking at a dog.] It means having someone call your cell phone to figure out where it is. Dog's stomach: Ring [The mathematical function "A(g 64 , g 64 )=" appears in the panel. Next to the equal sign stands a mathematician, clutching his head.] It means calling the Ackermann function with Graham's number as the arguments just to horrify mathematicians. Mathematician: Aughhh [An approximately 8 by 8 square of floor tiles is shown; the first, fourth, and seventh across in the first, fourth, and seventh rows are black, and the rest are white. A guy and girl are shown next to it, walking on what is presumed to be the same pattern of floor tiles.] It means instinctively constructing rules for which floor tiles it's okay to step on and then walking funny ever after. [Line indicating the uppermost right black tile: Black tiles okay.] [Line indicating tile directly below it: White tiles directly between black tiles okay.] [Line indicating a white tile in the last column over: Not okay.]

Regular Expressions

Regular Expressions

https://www.xkcd.com/208

https://www.explainxkcd.com/wiki/index.php/208:_Regular_Expressions

Whenever I learn a new skill I concoct elaborate fantasy scenarios where it lets me save the day. Megan: Oh no! The killer must have followed her on vacation! [Megan points to computer.] Megan: But to find them we'd have to search through 200 MB of emails looking for something formatted like an address! Cueball: It's hopeless! Off-panel voice: Everybody stand back. Off-panel voice: I know regular expressions. [A man swings in on a rope, toward the computer.] tap tap The word PERL! appears in a bubble. [The man swings away, and the other characters cheer.] A similar T-shirt in the xkcd store based on this comic says "stand back...I'm going to try science."

The comic begins with Randall saying how every time he develops a new skill, he finds himself daydreaming about using it to save the day. Computer skills aren't usually superhero material, which lends itself to the humor of the comic. In computing, a regular expression ("regex") provides a concise and flexible means to "match" (specify and recognize) strings of text, such as particular characters, words, or patterns of characters. Manually trying to look for a specific pattern through 200 MB of text is equivalent to looking for a needle in a haystack. But this task can be made easy by using regexes, since a script can read through text and match specific string patterns much faster than humans can achieve. Perl is a popular scripting language that has often been referenced favorably in the comic. Perl is also the most acknowledged language when it comes to the performance while evaluating regular expressions. [ citation needed ] The "PERL!" in the fifth panel is reminiscent of old superhero serials, particularly Batman (TV series) , in which sound effects such as "BAM!" "POW!" "ZAP!" would be displayed on screen in similar spiky bubbles. This fits with the theme of the comic, with Cueball being a "superhero" who fights crime using computer skills. The title text refers to how sensitive regexes can be to small mistakes or missing characters. In 1168: tar , another potential hero fails (and gets blown up by a nuclear bomb that is only able to be disarmed by typing in a valid tar command, but blows up if you don't do it on the first try) because the syntax of some commands and programming languages are just too difficult to remember by heart. Whenever I learn a new skill I concoct elaborate fantasy scenarios where it lets me save the day. Megan: Oh no! The killer must have followed her on vacation! [Megan points to computer.] Megan: But to find them we'd have to search through 200 MB of emails looking for something formatted like an address! Cueball: It's hopeless! Off-panel voice: Everybody stand back. Off-panel voice: I know regular expressions. [A man swings in on a rope, toward the computer.] tap tap The word PERL! appears in a bubble. [The man swings away, and the other characters cheer.] A similar T-shirt in the xkcd store based on this comic says "stand back...I'm going to try science."

Kayak

Kayak

https://www.xkcd.com/209

https://www.explainxkcd.com/wiki/index.php/209:_Kayak

[Beret Guy, in a kayak holding a paddle, is talking to Cueball, standing on a pier.] Beret Guy: Come explore the future with me! Cueball: Huh? What's that you're in? [Close up on Beret Guy and his kayak. The tip of the pier can be seen.] Beret Guy: A two seat kayak! Cueball: I see, but why do you have it? [Close up on Cueball. The tip of the kayak and the tip of the paddle can be seen. Beret Guy and the waterline cannot be seen.] Beret Guy: We'll find out! The future is a big place! Cueball: So the kayak travels through time? [Slightly zoomed-out version of the third panel. The tip of the paddle has disappeared but the waterline is visible again.] Beret Guy: Sure! Just like everything else! It also goes over water. Come on!

This comic deals with two linked themes, which both come under the umbrella of existentialism , a branch of philosophy. Beret Guy invites Cueball to join him in a two-seat kayak trip. However, Cueball is confused by his intention. Beret Guy initially words his invitation to Cueball as "come explore the future." However, this confuses Cueball, as he believes that Beret Guy's kayak can travel through time in a science fiction sense. In reality, Beret Guy is being more literal: after all, as the title-text emphasizes, "there's future everywhere;" everything is "traveling through time" simply by existing, as time is just another dimension. Beret Guy's comments show that he perceives all of life as an adventure, and just as exciting as time travel; his eagerness to "explore" it shows that he takes delight in the unpredictability of life. In this way, the comic criticizes people who become depressed with the lack of control they have over their future: Beret Guy suggests that, rather than continuously worrying, we should enjoy the thrill of the unknown. Cueball asks Beret Guy why he wishes for a kayak trip, as there is no intrinsic purpose or logic behind this action. However, Beret Guy claims that, in fact, nothing has any intrinsic purpose in the long run, and thus there is no reason not to go on a kayak trip. In this case, if a kayak trip is likely to make you happy, it is the right thing to do. In this way, the comic could be seen as criticizing those who do not take advantage of life's opportunities. Beret Guy's comments reference existentialism, which is a branch of philosophy that states that there is no intrinsic purpose or meaning to anything in life, as nothing will influence our eventual fate - death. It also states that there is no way of predicting what will happen to us, and that the future is always unknown. The solution is therefore to find one's own purpose in life, and make the most of life's opportunities while they are still available. The title text may be a reference to the Calvin and Hobbes collection book "There's treasure everywhere!" Making the most of life, and rationalizing the familiar, has also been explored in these comics: [Beret Guy, in a kayak holding a paddle, is talking to Cueball, standing on a pier.] Beret Guy: Come explore the future with me! Cueball: Huh? What's that you're in? [Close up on Beret Guy and his kayak. The tip of the pier can be seen.] Beret Guy: A two seat kayak! Cueball: I see, but why do you have it? [Close up on Cueball. The tip of the kayak and the tip of the paddle can be seen. Beret Guy and the waterline cannot be seen.] Beret Guy: We'll find out! The future is a big place! Cueball: So the kayak travels through time? [Slightly zoomed-out version of the third panel. The tip of the paddle has disappeared but the waterline is visible again.] Beret Guy: Sure! Just like everything else! It also goes over water. Come on!

90's Flowchart

90's Flowchart

https://www.xkcd.com/210

https://www.explainxkcd.com/wiki/index.php/210:_90%27s_Flowchart

90's Flowchart Start: The 90's? No: Stop Yes: Stop Hammertime or Collaborate, Listen

Here you can see an apparent flowchart. However, it has non-standard notation. The oval normally represents either the start or stop of a process. Here, both the yes and no end up in stop , which would normally imply that nothing below can be reached. Unless we are in the 90s, this doesn't matter, as there is nothing after the stop. But in the 90s, two processing paths follow, and both are from the lyrics of two-hit rap songs from the 90s: In both instances, the sense of the lyric is that you should interrupt what you are doing, and switch to the new action. Interpreted in terms of flowchart terminology, we could consider that the 'stop' just pauses the main thread, and secondary threads are launched to perform the 'Hammertime' and the 'Collaborate' and 'Listen' activities. The title text compares freestyle rapping with Markov chains . Markov chains are mathematical constructs in which the state at the next time step is dependent only upon the current state and probability, and not the state at previous times. This is somewhat similar to freestyle rapping, in which what is said next must bear some relationship to what was just said, but the "freestyle" part means that almost anything can be brought in (hence the probabilistic part); furthermore, freestyle rapping allows the rapper to say something next that bears a relationship to what was just said, but not to what was said before that. There have been several flowchart comics, all of which are listed here . Both Ice Ice Baby and U Can't Touch This were released in the year 1990, and so their status as "90s" music is disputable. The 1st decade didn't start until year 1 ( year 0 does not exist in the Georgian calendar system), so the 2nd decade didn't start until year 11, and the 3rd decade didn't start until year 21, etc. Whether those songs count as being released in the 90s would be discussed over 2000 comics later . 90's Flowchart Start: The 90's? No: Stop Yes: Stop Hammertime or Collaborate, Listen

Hamster Ball Heist

Hamster Ball Heist

https://www.xkcd.com/211

https://www.explainxkcd.com/wiki/index.php/211:_Hamster_Ball_Heist

[Cueball's Cueball-like friend tells him something.] Friend: You know that giant hamster ball you've always wanted? I just found out that Wayne Coyne from the Flaming Lips crowd-surfs in one. Cueball: Let's go. [Wayne Coyne, with curly hair and full beard, is crowd-surfing inside a giant hamster ball shown rolling from right to left with three lines behind it. He keeps his balance be leaning/walking forward and holding his arms out. The crowd shown begins to the right with a Cueball-like guy who the ball has just passed, and after him and below the ball there are 8 more people from the crowd all holding their hands up. The first four (a Hairy and three more Cueball-like guys) have already pushed it on, the next three (a person with black hair and two more Cueball-like guys) are touching the ball, and finally Megan is standing with her arms up waiting for the ball to arrive. Behind her are three of Cueball's Cueball-like friends, then Cueball, and finally to the far left partly outside the panel frame is yet another Cueball-like guy from the crowd. Above Cueball and to the edge of the hamster ball is a frame with a caption:] Some weeks later... Cueball: Ready? Friends: Ready [Cueball to the left and one of his friends to the right shove the crowd out of the way, causing the hamster ball with Wayne Coyne inside to fall to the ground, Wayne falling backwards with arms up. Cueball pushed three Cueball-like guys and a Megan into each other to the left, and one of his friends push four Cueball-like guys to the left, towards a fifth person only partly shown at the edge of the panel. (Cueball's other two friends are not shown; they could be in front and behind the ball doing the same, but not shown).] Cueball: Now! Wayne Coyne: Hey! Friend: Shove [Cueball and two of his friends start pushing the hamster ball with Wayne Coyne to the right, Coyne again stands up as before but to the right. He looks over his shoulder at the three who pushed him. To the left of the crowd, four Cueball-like guys (the third pointing at the scene and Megan) watch, and to the right, the third friend pushes a Cueball-like guy out of the way.] Cueball: Okay, push! Wayne Coyne: What's going on?! [Cueball and his two friends roll the hamster ball with Wayne Coyne up the ramp into the back of a truck, Wayne pushing the other way with both hands, while the third friend still holding the crowd back holding up his arms. Two Cueball-like guys from the crowd are shown also holding their arms up. At the front of the truck, a fourth Cueball-like friend stands by the door ready to drive.] Wayne Coyne: Help! [The truck drives off with the fourth friend in the front of the truck, leaving the crowd in a large cloud of dust. Four Cueball-like guys are shown in the first row of the crowd, which now is shown to consist of many people, shown behind with lots of small heads (Cueball-like) fading off in the distance.]

Wayne Coyne , the lead singer of the band The Flaming Lips , is indeed known to crowd-surf in a giant hamster ball . Hamster balls are a recurring subject on xkcd, starting with 152: Hamster Ball , which in direct relation to this comic showed that Cueball's biggest and only wish is such a ball. When Cueball's friend tells him about Wayne's hamster ball surfing, Cueball says "Let's go," suggesting that they should go and kidnap that hamster ball and Wayne. The rest of the comic outlines an elaborate mission to acquire a human-sized hamster ball by infiltrating a music concert and stealing the hamster ball while it is in use, thus also kidnapping the rock star, who would be structurally powerless to fight back while trapped within a spherical object. At least four Cueball-like guys help with the mission at the concert, one keeping the crowd back as the other three push the hamster ball into the waiting truck where a fifth friend acts as the driver when they escape with their heist. This has not been attempted, nor should be attempted in real life. [ citation needed ] The title text is one of Randall 's many open promises, claiming to supply anyone who does this in real life with a free T-shirt, and one for Wayne, too. It is later revealed in 577: The Race: Part 1 , that Cueball paid a large settlement for this heist. [Cueball's Cueball-like friend tells him something.] Friend: You know that giant hamster ball you've always wanted? I just found out that Wayne Coyne from the Flaming Lips crowd-surfs in one. Cueball: Let's go. [Wayne Coyne, with curly hair and full beard, is crowd-surfing inside a giant hamster ball shown rolling from right to left with three lines behind it. He keeps his balance be leaning/walking forward and holding his arms out. The crowd shown begins to the right with a Cueball-like guy who the ball has just passed, and after him and below the ball there are 8 more people from the crowd all holding their hands up. The first four (a Hairy and three more Cueball-like guys) have already pushed it on, the next three (a person with black hair and two more Cueball-like guys) are touching the ball, and finally Megan is standing with her arms up waiting for the ball to arrive. Behind her are three of Cueball's Cueball-like friends, then Cueball, and finally to the far left partly outside the panel frame is yet another Cueball-like guy from the crowd. Above Cueball and to the edge of the hamster ball is a frame with a caption:] Some weeks later... Cueball: Ready? Friends: Ready [Cueball to the left and one of his friends to the right shove the crowd out of the way, causing the hamster ball with Wayne Coyne inside to fall to the ground, Wayne falling backwards with arms up. Cueball pushed three Cueball-like guys and a Megan into each other to the left, and one of his friends push four Cueball-like guys to the left, towards a fifth person only partly shown at the edge of the panel. (Cueball's other two friends are not shown; they could be in front and behind the ball doing the same, but not shown).] Cueball: Now! Wayne Coyne: Hey! Friend: Shove [Cueball and two of his friends start pushing the hamster ball with Wayne Coyne to the right, Coyne again stands up as before but to the right. He looks over his shoulder at the three who pushed him. To the left of the crowd, four Cueball-like guys (the third pointing at the scene and Megan) watch, and to the right, the third friend pushes a Cueball-like guy out of the way.] Cueball: Okay, push! Wayne Coyne: What's going on?! [Cueball and his two friends roll the hamster ball with Wayne Coyne up the ramp into the back of a truck, Wayne pushing the other way with both hands, while the third friend still holding the crowd back holding up his arms. Two Cueball-like guys from the crowd are shown also holding their arms up. At the front of the truck, a fourth Cueball-like friend stands by the door ready to drive.] Wayne Coyne: Help! [The truck drives off with the fourth friend in the front of the truck, leaving the crowd in a large cloud of dust. Four Cueball-like guys are shown in the first row of the crowd, which now is shown to consist of many people, shown behind with lots of small heads (Cueball-like) fading off in the distance.]

Brain

Brain

https://www.xkcd.com/212

https://www.explainxkcd.com/wiki/index.php/212:_Brain

My Brain [Picture of Brain. Line points at a highlighted area.] Section that is devoted, no matter where I go in life, to planning the ultimate tree house*. *Oh man, it would be like Swiss Family Robinson, but with multiple trees connected by... hey come up to my room and see the blueprints!

The Swiss Family Robinson is a novel by the Swiss pastor and writer Johann David Wyss . In the novel, a shipwrecked family builds a tree house as good as a normal house complete with library and mechanical contraptions. Growing up, many children grow a fascination with tree houses. Tree houses are a child's own special place to do stuff away from their parents, have some autonomy, perhaps form a club. The obsession with tree houses usually fades once a child reaches their teenage years, but of course some of us never grow up. Being an adult geek/scientist who still enjoys childish things, Randall wants to build a sophisticated tree house rather than a simple one, taking the theme from the above-mentioned novel. The title text makes reference to the regular xkcd joke about how terrifying Velociraptors from the movie Jurassic Park are. But they never can reach a tree house, just because it's too high, as you can see here 87: Velociraptors . "Raptors" might refer to the informal bird group, hawks and owls and such, a joke relying on the previous infatuation with velociraptors. My Brain [Picture of Brain. Line points at a highlighted area.] Section that is devoted, no matter where I go in life, to planning the ultimate tree house*. *Oh man, it would be like Swiss Family Robinson, but with multiple trees connected by... hey come up to my room and see the blueprints!

Ghostbusters Marathon

Ghostbusters Marathon

https://www.xkcd.com/213

https://www.explainxkcd.com/wiki/index.php/213:_Ghostbusters_Marathon

[Cueball and a friend are in a room. Cueball is standing up. There is litter around them.] Cueball: Okay, that's all the Ghostbusters marathon I can handle. Later! Friend: You can't leave! We just started the animated series! Cueball: I've had my fill. I'm going home. Friend: I can't let you do that. [Cueball walks along a cord and past a box. The friend clicks a switch.] Click [Cueball is bathed in some kind of aura emitted by the box.]

Ghostbusters is a 1984 supernatural comedy film that spawned a sequel, a reboot, and two animated television series (the latter of which lasted less than a season, didn't feature the same cast of titular Ghostbusters, and therefore is probably being pointedly ignored). The box, a "Muon Containment Trap," is a device used in the film to capture ghosts. It is connected to a footswitch by a cable. The man trying to leave is about to be pulled into the box and held there indefinitely (against his will, of course). The title text refers to Julius Caesar's crossing of the Rubicon , a river (or very large stream) that marked the border between Roman Italy and an area of land Caesar was the appointed governor of. At the end of his term, the Roman Senate ordered him to disband his army and return to Italy. Instead, he brought his forces past the border, an act of treason and rebellion against the Republic, instigating the Roman Civil War. The phrase "crossing the Rubicon" now means making a move with gigantic consequences that cannot be undone. In the film Ghostbusters , the protagonists use "proton packs" that fire "streams" of energy. The inventor of the device warns that these streams should not be crossed against each other, as doing so "would be bad." Just how bad? "Try to imagine all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light." Important safety tip. Final quote taken from the 1984 movie Ghostbusters . [Cueball and a friend are in a room. Cueball is standing up. There is litter around them.] Cueball: Okay, that's all the Ghostbusters marathon I can handle. Later! Friend: You can't leave! We just started the animated series! Cueball: I've had my fill. I'm going home. Friend: I can't let you do that. [Cueball walks along a cord and past a box. The friend clicks a switch.] Click [Cueball is bathed in some kind of aura emitted by the box.]

The Problem with Wikipedia

The Problem with Wikipedia

https://www.xkcd.com/214

https://www.explainxkcd.com/wiki/index.php/214:_The_Problem_with_Wikipedia

[Heading above the chart:] The PROBLEM with WIKIPEDIA: [Text in a frame below the heading:] Tacoma Narrows Bridge [Lines lead down both left and right to two new frames with the following entries:] Suspension bridge Structural collapse [Two more lines lead down from the left frame and one from the right frame, and all lines end on a wiggling line from left to right. Below this wiggled line in square brackets it reads:] Three hours of fascinated clicking [Further below there is a similar wiggling line, from where six lines lead to new frames below:] William Howard Taft 24-hour analog dial Lesbianism in erotica [This frame is followed by a second:] Batman; Fatal hilarity Taylor Hanson [This frame is followed by a chain of two others:] Cotton; T-Shirt; Wet T-shirt contest

This comic illustrates the "problems" of information explosion coupled with a dense web of hypertext links . Through most of human history, written media has been both slow and linear. Hypertext allows a new type of information consumption, through small chunks of information linked together in a web of related concepts, and by being digital, each new chunk can be retrieved quickly and effortlessly. Wikipedia applies this principle very strongly, and because it covers so many topics, it is common for a reader to skim an article about a topic they need or want to know about, and end up following a series of links out of curiosity. Since each new page also has several links, the overall navigation pattern resembles a tree that branches out, "exploding" in size with each new level of link-clicking, thus resulting in many wasted hours (over three in this case) of reading stuff unrelated to the original goal, and lots of open browser tabs holding a wide variety of articles, which are seemingly unrelated, but have common "ancestors." (The problem, for Randall , of wasting time on Wikipedia was later referenced in the title text of 1501: Mysteries , and the more general problem of getting trapped following a never-ending chain of interesting links was covered in 609: Tab Explosion .) The large diversity in end links may also be a reference to the Wikipedia game . One can also see this effect occur in other MediaWiki -powered wikis such as this very website, where one comic can lead to another of similar relation or category. In the table below, a possible route for each entry has been found. Finding routes between the start and end points of the two pages above and the six below makes good challenges in the Wikipedia game . The title text refers to two of the articles that were supposedly reached at the bottom. William Howard Taft was the 27th President of the U.S., in office from 1909 to 1913, who was notorious for being so overweight that when a White House chief usher invented a story about him getting stuck in the White House bathtub , people took it seriously. A wet T-shirt contest is an exhibitionistic competition typically featuring young women contestants at a nightclub, bar, or resort. Clearly the combination of these two would be rather bizarre. There is an online game that involves trying to get from one Wikipedia page to another in the shortest possible route: http://thewikigame.com/ . Table of paths Due to the ever changing nature of Wikipedia, the Tacoma Narrows Bridge entry on Wikipedia no longer links to Structural collapse , requiring an intermediate step via Tacoma Narrows Bridge (1940) , and since Structural collapse now redirects to Structural integrity and failure , most pages on Wikipedia that linked to Structural collapse have been changed to rename this link. The table below lists one valid route for each destination article, though it is not necessarily the most efficient route. And that these routes may become invalid as articles are edited. They all have been updated on March 21, 2015. All links then could be found directly on the page. This was not the case in the original version of the paths, where some links were in hidden parts of the page. [Heading above the chart:] The PROBLEM with WIKIPEDIA: [Text in a frame below the heading:] Tacoma Narrows Bridge [Lines lead down both left and right to two new frames with the following entries:] Suspension bridge Structural collapse [Two more lines lead down from the left frame and one from the right frame, and all lines end on a wiggling line from left to right. Below this wiggled line in square brackets it reads:] Three hours of fascinated clicking [Further below there is a similar wiggling line, from where six lines lead to new frames below:] William Howard Taft 24-hour analog dial Lesbianism in erotica [This frame is followed by a second:] Batman; Fatal hilarity Taylor Hanson [This frame is followed by a chain of two others:] Cotton; T-Shirt; Wet T-shirt contest

Letting Go

Letting Go

https://www.xkcd.com/215

https://www.explainxkcd.com/wiki/index.php/215:_Letting_Go

[Cueball is holding a picture of himself and Megan in a heart; it has been ripped down the middle, separating the two people.] [Cueball sits at computer, looking at the picture.] [The panel has been inverted. Cueball still sits at the computer with the picture in front of him and his head drooped.] [Cueball types on the computer.] Text from computer: [email protected] :~# userdel megan

In fiction, a character who has had a romantic relationship end will be shown taking some act to remove a sign of their partner's presence in their life, e.g. removing/selling a wedding or engagement ring, removing the partner's toiletries from the bathroom, or deleting the partner's phone number from a cell phone. This is used to symbolize that the character has accepted the end of the relationship and is ready to move on, no longer pining for their loss or seeking to restore the relationship. The first three panels imply that Cueball was presumably in a now-terminated relationship with Megan . The final panel shows him using the Unix command 'userdel' to delete her user account from his computer. The joke here is that he considers this to be a significant part of accepting that she is no longer a part of his life, where most people would consider it a routine administrative task. The title text refers to Cueball's thankfulness that he never gave Megan the password to the administrator ('root') account on the computer. It is unclear why this is; he might be worried that she would have used the access to perform malicious actions after the breakup, or simply glad to be spared the need to change the root password. Alternately, it could be a metaphor for marriage and/or a closer emotional relationship, and he is glad that he did not allow her an even greater hold on his heart before the breakup (which would, of course, have entailed commensurately more pain when she did leave him). Not sharing the root password is indicative of a lack of trust in their relationship, which could be a factor in the initial breakdown. This was only the second time the name Megan was used in xkcd, the first time being in 159: Boombox . [Cueball is holding a picture of himself and Megan in a heart; it has been ripped down the middle, separating the two people.] [Cueball sits at computer, looking at the picture.] [The panel has been inverted. Cueball still sits at the computer with the picture in front of him and his head drooped.] [Cueball types on the computer.] Text from computer: [email protected] :~# userdel megan

Romantic Drama Equation

Romantic Drama Equation

https://www.xkcd.com/216

https://www.explainxkcd.com/wiki/index.php/216:_Romantic_Drama_Equation

TV Romantic Drama Equation (Derived during a series of 'Queer as Folk' episodes) [A table shows equations for possible romantic pairings in a TV show. The equation under "gay" is n(n-1) 2+x(x-n); the equation under "straight" is x(n-x).] x: Number of male (or female) cast members. n: total number of cast members. [A graph plots pairings (for large casts) against cast makeup. Each of the above equations forms a curve. "Gay cast" starts high for an all male cast, dips down at 50/50 cast makeup, and then rises again for all female. "Straight cast" starts at zero for an all male cast, peaks at 50/50 cast makeup, and then drops to zero again for an all female cast. The two curves intersect at two points close to the middle.]

In a group of n people, such as the cast of a TV romantic drama like Queer as Folk , the number of possible different pairs of people is n(n-1)/2. A romantic drama will often consider, over time, many possible romantic pairs of its cast members, even seeming to test the limit of how many pairs are possible. Through an austerely binaristic lens, this comic explores the implication of sex and sexual orientation in characterizing the possible pairs. If everyone in the group is male or female, then each pair could be classified as gay or straight. The formulas in the comic give how many of the possible pairs are gay and how many are straight, as a function of the total number of people and how many are male (or, equivalently, how many are female.) For example, of the 9 principal cast of Firefly, 5 are men and 4 are women. With n=9 and x=5, we have 16 possible gay pairs and 20 possible straight pairs. A graph shows how the relative number of males and females affects the number of gay pairs and straight pairs. When the group is all male (or all female), all of the possible pairs are gay, but as the minority sex's number is increased, more of the pairs are straight. When the group is half male and half female, the number of straight pairs is maximized, and straight pairs slightly outnumber gay pairs. The curves are labeled "gay cast" and "straight cast", perhaps alluding that a "gay cast" would consider only gay pairs, and a "straight cast" would consider only straight pairs. There is a note that the graph describes large casts. Because all the quantities involved are discrete, for a small [n] there are only a few points to plot on the graph, and the smooth, continuous curves seen in the comic are less recognizable. The title-text mentions that Randall made a graph of his prospective dating pool over time and was depressed by the results. As he gets older, his dating pool gets smaller: fewer people his age are single. But as Randall later shows in 314: Dating Pools , age is not the problem--he is! The formulas may be derived as follows: Each straight pair needs to include one of the x males and one of the (n-x) females, so there are x(n-x) possible ways of combining one of each. E.g., if there are n=5 people, of whom x=2 are male, then there will be 3 possible pairings involving the first male, and 3 possible pairings involving the second, yielding 2(5-2)=6 possible pairs. Wolfram|Alpha: x*(n-x) Each gay pair needs to include either two males or two females. To choose two males, we can start with any of the x males and choose any of the (x-1) remaining males. However, that counts each possible pair twice. E.g., Adam&Steve got counted when we chose Adam first and Steve second, and again when we chose Steve first and Adam second. To avoid double-counting the pairs, we therefore need to divide the product by 2. So there are x(x-1)/2 possible pairs of two males. Similarly, there are (n-x)(n-x-1)/2 possible pairings of two females. Summing these, we get the total number of possible gay pairs as [x^2 - x + n^2 - nx - n - xn + x^2 + x]/2. That simplifies to [n^2 - n + 2 x^2 - 2 xn]/2. The left two terms can be combined together as n(n-1) and the right two terms can be combined together as -2x(n-x) or 2x(x-n) [which is negative, because x-n<0]. Since the sum of these terms was divided by 2, we get that the total number of possible gay pairs is n(n-1)/2 - x(n-x), or n(n-1)/2 + x(x-n), which is what the cartoon says. Wolfram|Alpha: n*(n-1)/2+x*(x-n) TV Romantic Drama Equation (Derived during a series of 'Queer as Folk' episodes) [A table shows equations for possible romantic pairings in a TV show. The equation under "gay" is n(n-1) 2+x(x-n); the equation under "straight" is x(n-x).] x: Number of male (or female) cast members. n: total number of cast members. [A graph plots pairings (for large casts) against cast makeup. Each of the above equations forms a curve. "Gay cast" starts high for an all male cast, dips down at 50/50 cast makeup, and then rises again for all female. "Straight cast" starts at zero for an all male cast, peaks at 50/50 cast makeup, and then drops to zero again for an all female cast. The two curves intersect at two points close to the middle.]

e to the pi Minus pi

e to the pi Minus pi

https://www.xkcd.com/217

https://www.explainxkcd.com/wiki/index.php/217:_e_to_the_pi_Minus_pi

Cueball: Hey, check it out: e π − π is 19.999099979. That's weird. Black Hat: Yeah. That's how I got kicked out of the ACM in college. Cueball: ...what? Black Hat: During a competition, I told the programmers on our team that e π − π was a standard test of floating-point handlers -- it would come out to 20 unless they had rounding errors. Cueball: That's awful. Black Hat: Yeah, they dug through half their algorithms looking for the bug before they figured it out.

e is a mathematical constant roughly equal to 2.71828182846. π is another, roughly equal to 3.14159265359. The first panel discusses e π − π, which is around 19.999099979 — very close to 20. Black Hat explains how he tricked a programming team into believing that e π − π really equals 20 — instead of just being weirdly close — thus that any noticeable deviation from 20 results from errors in the code. This made them waste a lot of time trying to find a nonexistent bug until they realized that Black Hat was lying (clearly they had not known him for very long, and clearly they weren't very knowledgeable in mathematics). Floating point numbers are how computers store non-integer real numbers as decimals — or rather, in most cases, approximate them: infinite amounts of data would be required to represent most numbers in decimal form (exceptions are integers and terminating decimals ). The "floating-point handlers" would be the code performing the e π − π calculation. ACM is the Association for Computing Machinery , which at the time of writing sponsored the International Collegiate Programming Contest . It is likely that it was this competition, in which Black Hat wasted his teams time, for which he got kicked out. Some random facts about the math here: The title text pokes fun at another coincidence: ∜(9² + 19²/22) ≈ 3.1415926525, equating close to π (deviating only in the 9th decimal place). The humor comes from the fact that π is transcendental . Transcendental numbers are numbers that cannot be expressed through basic arithmetic with integers; one cannot end up with the exact value for any transcendental number (including π) by adding, subtracting, multiplying, dividing, exponentiating, and/or taking the nth root of any rational number, meaning the title text cannot possibly be true. A much later comic, 1047: Approximations , puts forth quite a few more mathematical coincidences. Cueball: Hey, check it out: e π − π is 19.999099979. That's weird. Black Hat: Yeah. That's how I got kicked out of the ACM in college. Cueball: ...what? Black Hat: During a competition, I told the programmers on our team that e π − π was a standard test of floating-point handlers -- it would come out to 20 unless they had rounding errors. Cueball: That's awful. Black Hat: Yeah, they dug through half their algorithms looking for the bug before they figured it out.

Nintendo Surgeon

Nintendo Surgeon

https://www.xkcd.com/218

https://www.explainxkcd.com/wiki/index.php/218:_Nintendo_Surgeon

Scary Thought #137: The NES came out over two decades ago. Those kids are all grown-ups now. [Two surgeons are in an operating room, leaning over a patient.] First Surgeon: He's going into cardiac arrest. Stand by for defibrillation. Second Surgeon: Wait. First let's try taking out the heart, blowing into the ventricles, and putting it back in.

The Nintendo Entertainment System , released in North America in 1985, helped revitalize the video-game industry after the video-game crash of 1983, with such games as the Super Mario Bros. series, The Legend of Zelda , the Mega Man series, Castlevania , and Metroid helping it stand alone as what is still considered by many people today, the greatest video-game console of all time. However, it was notorious for glitching games upon start-up, due in no small part to the unusual shape of the game console, which required one to open the door, push the game cartridge inside, push down to lock it in place, and push the power button. The console was deliberately designed this way so that it wouldn't look like a regular video-game console (and wouldn't be associated with the still-fresh stigma of the video-game crash only two years previous), but it caused no end of pain for people wanting to play the games. It would work fine for about two years, but after that "cartridge tilt" would become a problem as either the game's or the console's electric contacts could become misaligned. A ubiquitous fix for this problem among gamers was to take the cartridge out, blow into it, and put it back inside, all to clean out any dust inside the cartridge that would make "cartridge tilt" worse and occur more frequently. This was not a recommended solution by Nintendo of America, and didn't always work, but it worked frequently enough to enter gamer culture, and even today, people who had the NES as children remember having to do that. The NES was 22 years old as of the date this comic was written. Someone who was 10 years old when they got their Nintendo for Christmas could very well be old enough in 2007 to have attained their doctorate degree, and so this comic hearkens back to the aforementioned cartridge fix by suggesting that a heart surgeon might try that on a real-life heart patient. And like the introduction states, that is a scary thought. The title text is one of many xkcd references to the terrifying Velociraptor predator from the dinosaur movie Jurassic Park . Scary Thought #137: The NES came out over two decades ago. Those kids are all grown-ups now. [Two surgeons are in an operating room, leaning over a patient.] First Surgeon: He's going into cardiac arrest. Stand by for defibrillation. Second Surgeon: Wait. First let's try taking out the heart, blowing into the ventricles, and putting it back in.

Blanket Fort

Blanket Fort

https://www.xkcd.com/219

https://www.explainxkcd.com/wiki/index.php/219:_Blanket_Fort

[Megan and Ponytail are talking with each other. There is a fort made of cushions and blankets on the left.] Megan: Like my fort? It uses every blanket and cushion in the apartment. Ponytail: Okay, no offense, but this is like that ball pit you made -- Cute, but don't you worry you're clinging to childhood games because you're afraid of change? Megan: No. I'm happy to grow up. But I won't pretend fun things aren't still fun out of fear of looking silly. Ponytail: But you're 24 and building blanket forts. How have you changed? What's adult about that? Megan: Well, there's my boyfriend curled up in the back. Ponytail: ...Ah. Boyfriend [from inside the fort]: Excuse my shyness. I'm not exactly dressed.

In an apparent continuation of comic 150: Grownups , Megan is showing off a blanket fort to her friend Ponytail . Ponytail answers that Megan's childishness stems from a fear of growing up. Megan responds that she's fine with growing up. She sees her behavior as a mature realization that some of the things she enjoyed as a child are still enjoyable. When pressed for evidence that she has in any way become an "adult," it is revealed that her boyfriend is inside the blanket fort. He has not spoken because he fears to be found by them when "not exactly dressed," thus implying that "adult" activities had been going on in the fort. The title text provides another example of this: They built a fort in the woods, another type of fort that a kid would love to have, but then used it to hide a body. This implies that they killed someone, which is not usually something associated with children. [ citation needed ] A hooker is also more formally known as a prostitute , which is also not usually something associated with children. [ citation needed ] [Megan and Ponytail are talking with each other. There is a fort made of cushions and blankets on the left.] Megan: Like my fort? It uses every blanket and cushion in the apartment. Ponytail: Okay, no offense, but this is like that ball pit you made -- Cute, but don't you worry you're clinging to childhood games because you're afraid of change? Megan: No. I'm happy to grow up. But I won't pretend fun things aren't still fun out of fear of looking silly. Ponytail: But you're 24 and building blanket forts. How have you changed? What's adult about that? Megan: Well, there's my boyfriend curled up in the back. Ponytail: ...Ah. Boyfriend [from inside the fort]: Excuse my shyness. I'm not exactly dressed.

Philosophy

Philosophy

https://www.xkcd.com/220

https://www.explainxkcd.com/wiki/index.php/220:_Philosophy

[Megan sits on a chair for two panels without moving.] [In the third panel, Megan has still not moved but makes the following comment to no one in particular.] Megan: If the question of what it all means doesn't mean anything, why do I keep coming back to it? [Two Cueball-like friends of Megan are talking to each other. One of them is standing behind the office chair in which the other friend is sitting, behind a desk with a computer. The standing friend starts to walk toward Megan. The sitting friend pulls a large yellow and green super soaker from a drawer.] Standing friend: She's getting existential again. Sitting friend: It's okay, I have a super soaker.

In all of philosophy , perhaps the most important questions consider the meaning of life and can be expressed as "Why are we here?" or "What does it all mean?" Many philosophers and theologians have attempted to answer the question over the course of human history, and every religion claims to have some sort of answer. Megan has been considering that the question is essentially meaningless. However, if that is true, she can't understand why it continues to be in her thoughts. This might feel frustrating for Megan. Two of her friends (both Cueball -like) notice that she is seemingly stuck in this existential question and have a short-term solution for her. One friend reaches for a Super Soaker 50, a powerful toy squirt gun, to shoot at Megan while she is having an existential crisis . (Megan uses this soaker later against Cueball in 517: Marshmallow Gun and 2334: Slide Trombone , and in comic 625: Collections , she has another one of her crises.) The title text refers to the operant conditioning technique (a form of behavioral modification) commonly used with house cats. If they start scratching the furniture, many people spray them with a squirt bottle (since they hate water) to discourage that behavior (though it seldom works). It may also allude to the idea of hitting a break key where a program is stuck in a logical loop. Megan has since this comic had existential crises both in 1111: Premiere and in 1822: Existential Bug Reports . [Megan sits on a chair for two panels without moving.] [In the third panel, Megan has still not moved but makes the following comment to no one in particular.] Megan: If the question of what it all means doesn't mean anything, why do I keep coming back to it? [Two Cueball-like friends of Megan are talking to each other. One of them is standing behind the office chair in which the other friend is sitting, behind a desk with a computer. The standing friend starts to walk toward Megan. The sitting friend pulls a large yellow and green super soaker from a drawer.] Standing friend: She's getting existential again. Sitting friend: It's okay, I have a super soaker.

Random Number

Random Number

https://www.xkcd.com/221

https://www.explainxkcd.com/wiki/index.php/221:_Random_Number

[A computer program.]

The comic specifies a function (in a C similar syntax), which judging by its name should be designed to return a random number. Most functions of this form are random number generators , meaning that on subsequent calls they return different random numbers. But the programmer has instead implemented a function that just returns the same random number each time, which, while it could indeed have been truly randomly chosen by rolling a die as the comment documented, is essentially worthless were it ever to be called more than once (with the expectation of different, i.e., random, results). In other words, the results over time would not be random at all, but completely predictable and deterministic. The IEEE is the organization responsible for maintaining a number of computer standards. An RFC, or Request for Comments , is a formal document put out to computing experts by IETF in the hopes of becoming a future standard. However, RFC 1149 was an April Fools' joke , defining how carrier pigeons can be used to transmit Internet packets. "RFC 1149.5," meanwhile, simply does not exist. [A computer program.]

Small Talk

Small Talk

https://www.xkcd.com/222

https://www.explainxkcd.com/wiki/index.php/222:_Small_Talk

[Two Cueballs standing next to each other]: [Header box on top of the panel:] Sometimes I forget how to do small talk. Friend: Hey! Cueball: Hey, man! Friend: What's up? How've you been? Cueball: Well... [Three overlapping identical frames of the two Cueballs standing next to each other indicate the passage of time.] [The Cueball on the left snaps his fingers at the Cueball on the right.] Friend: Uh, you ok? Cueball: Yeah! It's just an interesting question. I'm trying to decide what best sums up my-- Friend: Hey. Conversation. Cueball: Oh, right. I'm fine. You? Snap

Cueball is approached by his friend who offers one of the standard greetings of, "What's Up? How've you been?" In standard "small talk," an appropriate answer would be only one or two words (e.g. "Fine" or "Pretty good"). These are generally positive responses, with negative ones only offered in extreme circumstances. In this situation, Cueball forgets that this type of answer is what his friend is expecting. Instead, he contemplates thoroughly on his condition, wanting to provide accurate, detailed information to his friend. His response sheds light on the many layers of meaning a simple question such as "What's up?" can have. His friend, thrown off by the delayed response, snaps his fingers to regain Cueball's attention and reminds him that they are having a conversation, which is best facilitated by the standard short responses. The title text shows that Cueball was more interested in accuracy than the ease of the conversation, simply out of respect for his friend. This was one of the earliest examples of problems with social interactions for Cueball (or Randall ). Since this comic it has been a recurring theme on xkcd. It is especially similar to the much later 1961: Interaction . [Two Cueballs standing next to each other]: [Header box on top of the panel:] Sometimes I forget how to do small talk. Friend: Hey! Cueball: Hey, man! Friend: What's up? How've you been? Cueball: Well... [Three overlapping identical frames of the two Cueballs standing next to each other indicate the passage of time.] [The Cueball on the left snaps his fingers at the Cueball on the right.] Friend: Uh, you ok? Cueball: Yeah! It's just an interesting question. I'm trying to decide what best sums up my-- Friend: Hey. Conversation. Cueball: Oh, right. I'm fine. You? Snap

Valentine's Day

Valentine's Day

https://www.xkcd.com/223

https://www.explainxkcd.com/wiki/index.php/223:_Valentine%27s_Day

Valentine's Day [There is a large, shaded, red heart.] Because love isn't quite complicated enough as it is.

As mentioned in the comic, love is already pretty complicated, even more so on Valentine's Day . Valentine's Day makes it more complicated by introducing all kinds of questions. Is our relationship such that it should be acknowledged on Valentine's Day? If so, how? If by a card, what kind of card would be best? If by something more than a card, what? Candy? Flowers? A Date? What does the Valentine I received really mean? Friendship? Love? A covert request for sex? (see 63: Valentine - Heart ). As an example of the kinds of dilemmas that can arise, see also 1016: Valentine Dilemma . The phrase "Because love isn't quite complicated enough as it is" is an obvious use of sarcasm , as love is really complicated, according to Randall ( see above ). Referenced in the title text, Joey Comeau is the author of the webcomic A Softer World . It is a queer comic whose work also discusses love in various forms, so between them, Randall Munroe and he are a good team to consider working on "subverting the hetero-normative paradigm." Heteronormativity is the body of lifestyle norms holding that people fall into two distinct genders with natural and complementary roles in life. Whether or not anything that cartoons can do would fix the Valentine's Day problem is another issue. Among other things, ditching the hetero-normative paradigm presumably complicates things in terms of potential love relationships, which now include more possibilities than male-female, as is shown in 216: Romantic Drama Equation . All of these might face the Valentine's Day issues in various ways. Valentine's Day [There is a large, shaded, red heart.] Because love isn't quite complicated enough as it is.

Lisp

Lisp

https://www.xkcd.com/224

https://www.explainxkcd.com/wiki/index.php/224:_Lisp

[Floating in space.] Speaker: Last night I drifted off while reading a Lisp book. Cueball: Huh? Speaker: Suddenly, I was bathed in a suffusion of blue. [Floating in space before a vast concept tree.] Speaker: At once, just like they said, I felt a great enlightenment. I saw the naked structure of Lisp code unfold before me. Cueball: My God Cueball: It's full of 'car's Speaker: The patterns and metapatterns danced. Syntax faded, and I swam in the purity of quantified conception. Of ideas manifest. [Close-up of floating in space before part of a concept tree.] Truly, this was the language from which the gods wrought the Universe. [Floating in space with God appearing through a line of clouds.] God: No, it's not. Cueball: It's not? God: I mean, ostensibly, yes. Honestly, we hacked most of it together with Perl.

Lisp is a computer programming language with simple, highly regular syntax. The language's most notable feature is that programs take the same form as the language's primary data structure (the linked list). This blurs the line between code and data and permits programs to inspect and even alter their own source code, thereby opening up deep opportunities for metaprogramming . Lisp is also a functional programming language (though not purely functional, as some more recent languages are ), meaning that programs are expressed in terms that are simple elaborations or extensions of the lambda calculus , a formal mathematical model of computation. This gives programs written in functional languages such as Lisp a distinctively abstract, mathematical form that is commonly considered difficult to fully grok (see 1270: Functional ). The phrase A suffusion of blue is a reference to Douglas Adams ' book The Long Dark Tea-Time of the Soul . In it, an I Ching calculator calculates that everything above the value of 4 is a suffusion of yellow . In the comic, Cueball marvels at the fundamental and complete nature of the language of creation that he sees in his dream. In the Lisp programming language, "car" is a primitive (i.e. basic) function that produces the first item in a list. The line "My God, It's full of ' car 's" is a pun, most likely referring to the movie 2010: The Year We Make Contact , the sequel to 2001: A Space Odyssey . In the book 2001: A Space Odyssey , when astronaut David Bowman accidentally activates a star gate, he exclaims as he enters it "The thing's hollow — it goes on forever — and — oh my God - it's full of stars!", although he does not say anything in the first movie during the final sequence. This likely also includes a transitive reference a chapter in The Little Schemer , a popular introductory Lisp book, called *Oh My Gawd*: It's Full of Stars , also itself a reference to 2001. In the second panel, Cueball remarks that, "At once, just like they said, I felt a great enlightenment." This is a reference to a pattern of observations among programmers and computer scientists that while Lisp often seems alien or arcane — even deliberately so, even to experienced hackers, even with repeated exposure over time — truly understanding Lisp in a deep, non-superficial way, results in a profound epiphany, a sudden and abiding illumination wherein one's preconceived notions about computation and programming are fundamentally transfigured, oftentimes over the course of a very short span such as during a single all-day hacking binge. Lispers commonly describe the experience as being akin to learning programming for the first time again ; Daniel P. Friedman (author of much ground-breaking research and many popular introductory texts on Lisp and programming language design) described it as "[learning] to think recursively ," and contended that " thinking about [functional] computing is one of the most exciting things the human mind can do ." Cueball's remarks about patterns, metapatterns, and the disappearance of syntax are reactions to the elegant simplicity of the Lisp programming language, in which it is relatively easy to build immensely sophisticated programs using simple recursive elaborations of structure. This is fundamentally unlike the much more typical and common imperative programming languages , in which programs are written as chains of instructions for the machine to follow. Cueball then, in the third, borderless panel, muses that this has to have been the language the gods used to create the universe, which is a pretty bold statement that Cueball seems to make because he views Lisp as something flawless and perfect, as these are qualities that often subjectively apply to things that people, like Cueball, claim to have been made or used by gods or other holy beings. A cloudy, bearded man, presumably representing God, states that this is untrue, and after a surprised inquiry from Cueball replies that the universe was actually hacked together with the programming language Perl . Perl employs an idiosyncratic syntax that borrows liberally from a number of other languages. Although a versatile language often employed for assembling projects quickly (the much-loved Programming Perl introduces it as "[the] language for getting your job done "), Perl has a reputation for being ugly and inelegant, partly as a result of its pidgin-like fusion of many inconsistent language elements and code styles. It was famously described as a " Swiss-Army chainsaw," because it is very powerful but also unwieldy and unattractive. By way of contrast to Daniel Friedman above, Larry Wall , the creator of Perl, criticized the highly cerebral Lisp attitude toward programming with the words The joke is that the Creator, like many software developers, was a bit rushed and chose to quickly throw together a working prototype rather than do the job right from the beginning; concurrently, that Cueball, thinking he has discovered an amazing and beautiful secret in the hidden world of Lisp, learns that in fact the real world is filled with ugly hacks and quick-and-dirty imperative code. A (possible) hidden joke might be an oblique reference to Greenspun's tenth rule when God replies with "I mean, ostensibly, yes." Greenspun's tenth rule says that any sufficiently complex program written in another high level programming language will necessarily contain an imperfect, undocumented, slow, and bug-ridden implementation of about half of Common Lisp . Greenspun's tenth rule was meant to express the belief that Common Lisp, a large, full-featured Lisp dialect, is so flexible and robust that any attempt to render any really sophisticated program in most other languages requires the programmer to expend extraordinary effort unwittingly reinventing, in needlessly convoluted fashion, features and systems that would be elegant and trivial in Common Lisp. This explains why such a program might look or feel "Lispy" to an unfamiliar observer, and why the universe (if viewed as such a program) might look to mathematicians and scientists as though it probably has a beautifully simple mathematical basis, even if in reality it was just hacked together with a bunch of ersatz, special-case rules. The title text continues the analogy by suggesting that the theory of quantum mechanics was written in regular expressions ("regexes"), a complex language for pattern matching used heavily in Perl. Regular expressions are often criticized as being a write-only language , that is, a language so complicated in syntax that any significant program written in them cannot be understood by anybody (often not even the original author). Documentation is essential to assist in the understanding of complex regular expressions. The title text claims that at some point, the documentation for quantum mechanics was lost, which explains why quantum mechanics is so bizarre and counterintuitive. [Floating in space.] Speaker: Last night I drifted off while reading a Lisp book. Cueball: Huh? Speaker: Suddenly, I was bathed in a suffusion of blue. [Floating in space before a vast concept tree.] Speaker: At once, just like they said, I felt a great enlightenment. I saw the naked structure of Lisp code unfold before me. Cueball: My God Cueball: It's full of 'car's Speaker: The patterns and metapatterns danced. Syntax faded, and I swam in the purity of quantified conception. Of ideas manifest. [Close-up of floating in space before part of a concept tree.] Truly, this was the language from which the gods wrought the Universe. [Floating in space with God appearing through a line of clouds.] God: No, it's not. Cueball: It's not? God: I mean, ostensibly, yes. Honestly, we hacked most of it together with Perl.

Open Source

Open Source

https://www.xkcd.com/225

https://www.explainxkcd.com/wiki/index.php/225:_Open_Source

[The first panel has the second panel inside it. It also has a slightly light gray background color. Just above the inlaid second panel is Richard Stallman lying in his bed sleeping, the bottom part at the foot of the bed hidden behind the second panel below. Below his bed under his head lies a katana sword in its sheath, and another one hangs in its sheath behind the end of the bed. Two ninjas with swords and black cloths around their heads jump through the skylight, smashing it so glass scatters around them. Each of them is hanging one-handed from the same rope coming down from the skylight. The rope ends just above the inlaid frame below. The two ninjas shout at Richard Stallman, from four speech bubbles that have pointy ends to indicate how the two alternately speak. (These bubbles are white, not gray.)] Richard Stallman: Zzzz Top Ninja: Richard Stallman! Your viral open source licenses have grown too powerful. Bottom Ninja: The GPL must be stopped. Top Ninja: At the source. Bottom Ninja: You. [In the second inlaid panel (with normal white background), Richard Stallman wakes up immediately, and while sitting up in bed, he pulls out both his katana swords from their sheaths, leaving the sheaths under and behind the bed. One hand is up in the air with the sword from behind the bed, and the other is still pointing down with the swords from below the bed. Lines indicate the fast movement of the swords. His three speech bubbles are like those of the ninjas, the last two even breaking the panel entering into the large first panel.] Katana swords: Shing! Shing! Richard Stallman: Hah! Microsoft lackeys! So it has come to this! Richard Stallman: A night of blood I've long awaited. But be this my death or yours, free software will carry on! For a GNU dawn! For freedom! Richard Stallman: ...Hey, where are you going? [An outside scene at night with black sky. Richard Stallman's gray house can be seen with the broken white skylight on the roof. The ninjas are jumping out of a window at ground height while taking off their ninja cloth around their heads, holding them in their hand, thus revealing that they both look like Cueball. The first one is already on the grassy ground beneath the window, his sword pointing down and to the left; the other just jumps from the window pane, his sword pointing up and to the right. Again, they have speech bubbles like before. It is not possible to tell which of the two ninjas from before is first out the window.] Ninja in window: Man, you're right, that never gets old. Ninja on the grass: Let's do Eric S. Raymond next. Ninja in window: Or Linus Torvalds. I hear he sleeps with nunchucks.

Richard Stallman , or rms after his handle, is an old-school hacker known for establishing the Free Software Foundation (FSF) and initiating the GNU Project in the early 1980s, which produced major portions of what would later be the GNU/Linux [1] operating system. In this capacity, he's also known for being one of the most ardent and outspoken proponents of open source software , often referred to by Stallman as free software . In fact, his advocacy is so emphatic and polemical that he has garnered active dislike from traditionalists who believe that software source code should be retained as a trade secret by its developer(s). Stallman has expressed that he did not even wish to be in a comic using the phrase Open Source (see the trivia section). While this dislike may not rise to the level of hiring ninja assassins to remove him from the world though that is historically inaccurate, it is strong. The joke of the comic, as it also turns out, is that the two Cueballs dressed up as ninjas were just out to have a fun time teasing Stallman, and they seemed to know that Stallman's paranoia about Microsoft makes him sleep with no fewer than two katana swords near his bed. This type of sword was one of the traditionally made Japanese swords that were used by the samurai of feudal Japan mainly as a sidearm. A ninja or more accurately a Shinobi no mono was basically special forces in feudal Japan. They specialized in espionage, sabatoge, etc. they were a rough combination of MI6, CIA, and Navy SEAL in feudal japan. Although they did not specialize in assassinations, that is something that they could do. Although samurai could also be shinobi/ninjas if they chose to do that job, samurai is a social class while shinobi no mono/ninjas were a job, not a social class. So this makes sense in this comic with Stallman, the samurai, and the ninjas, the lackeys of the oppressing Microsoft (at least in his mind). It also turns out that they specifically choose targets for their raids who have reason to be paranoid of larger companies that might send someone after them, and thus sleep with weapons near their beds. Stallman has received a Katana due to this comic (see the trivia section). GPL refers to the 'GNU General Public License', which is a copyright license written by the FSF that covers much GNU software and plenty of other free software besides. It stipulates that software so copyrighted must always be provided along with full source code, and that everyone in possession of such software is free to use, study, modify, and redistribute it for any purpose whatsoever (including sale or resale), provided they give due credit to any other contributing developers and provide access to the complete source code and retain all copyright notices. Legally, this gives all users of such software exactly the same rights under copyright as the developer(s) and prevents any developers from ever taking away those rights from users, which is the defining feature of ' free-as-in-libre ' software. It also has the effect of making all software derived from GPL software thereby also GPL, even if 'derived' merely means 'borrowed a few lines of code from'. Some (e.g. Microsoft's Steve Ballmer ) have therefore argued that this makes GPL software behave as a kind of 'license virus' , which spreads GPL-guaranteed freedoms to any software used in close conjunction with GPL'd software during development, such that businesses should actively avoid adopting free and open source software , so as not to jeopardize software developers' legal standing with regard to proprietary IP copyrights . During the attack, Richard Stallman begins to speak like he quotes an old play. For instance, the wording "For a GNU dawn!" is pronounced "For a g'new dawn!", following the pronunciation of GNU , so it is a version of New Dawn , a sentence used often in fiction. He even gets annoyed when it turns out that the ninjas just run away. He had clearly waited a long time to, even looking forward to, defending himself with his katanas. Because the two "ninjas" had so much fun pranking Stallman, they plan to do more of these raids, even mentioning two other possible future targets on their way out of the window: Eric S. Raymond is a famous hacker who wrote The Cathedral and the Bazaar and has been something of an unofficial spokesperson for open source as a software development methodology . The plan to prank Eric Raymond could be a bad one, since he is an experienced martial artist, swordsman, and firearm enthusiast. However, this seems to be the attraction of these two "ninjas," as can be seen by what they seem to know about their other possible target: Linus Torvalds is the creator of the Linux kernel , a free/open source operating system kernel inspired by the Unix kernel, which proved to be the final component that, combined with then pre-existing GNU system functions and userland components, produced the first fully free operating system, Linux . The plan to prank Torvalds would at first sound more boring as the mild-mannered Finn , while known to be strongly, abrasively opinionated, is otherwise mostly harmless. However, one of the ninjas seems to know otherwise, since it is rumored that Linus sleeps with nunchucks in the same way that Stallman sleeps with two katana swords. The nunchaku is a traditional Okinawan martial arts weapon consisting of two sticks connected at one end by a short chain or rope. A third possible target of this prank is mentioned in the title text. Ralph Nader is a famous consumer rights advocate, most famous for his controversial 2000 presidential run , and the 1965 book Unsafe at Any Speed . Nader is an environmentalist and a member of the Green Party, and he supports clean energy, thus naturally being opposed to "Big Oil" companies. [The first panel has the second panel inside it. It also has a slightly light gray background color. Just above the inlaid second panel is Richard Stallman lying in his bed sleeping, the bottom part at the foot of the bed hidden behind the second panel below. Below his bed under his head lies a katana sword in its sheath, and another one hangs in its sheath behind the end of the bed. Two ninjas with swords and black cloths around their heads jump through the skylight, smashing it so glass scatters around them. Each of them is hanging one-handed from the same rope coming down from the skylight. The rope ends just above the inlaid frame below. The two ninjas shout at Richard Stallman, from four speech bubbles that have pointy ends to indicate how the two alternately speak. (These bubbles are white, not gray.)] Richard Stallman: Zzzz Top Ninja: Richard Stallman! Your viral open source licenses have grown too powerful. Bottom Ninja: The GPL must be stopped. Top Ninja: At the source. Bottom Ninja: You. [In the second inlaid panel (with normal white background), Richard Stallman wakes up immediately, and while sitting up in bed, he pulls out both his katana swords from their sheaths, leaving the sheaths under and behind the bed. One hand is up in the air with the sword from behind the bed, and the other is still pointing down with the swords from below the bed. Lines indicate the fast movement of the swords. His three speech bubbles are like those of the ninjas, the last two even breaking the panel entering into the large first panel.] Katana swords: Shing! Shing! Richard Stallman: Hah! Microsoft lackeys! So it has come to this! Richard Stallman: A night of blood I've long awaited. But be this my death or yours, free software will carry on! For a GNU dawn! For freedom! Richard Stallman: ...Hey, where are you going? [An outside scene at night with black sky. Richard Stallman's gray house can be seen with the broken white skylight on the roof. The ninjas are jumping out of a window at ground height while taking off their ninja cloth around their heads, holding them in their hand, thus revealing that they both look like Cueball. The first one is already on the grassy ground beneath the window, his sword pointing down and to the left; the other just jumps from the window pane, his sword pointing up and to the right. Again, they have speech bubbles like before. It is not possible to tell which of the two ninjas from before is first out the window.] Ninja in window: Man, you're right, that never gets old. Ninja on the grass: Let's do Eric S. Raymond next. Ninja in window: Or Linus Torvalds. I hear he sleeps with nunchucks.

Swingset

Swingset

https://www.xkcd.com/226

https://www.explainxkcd.com/wiki/index.php/226:_Swingset

[Woman talking to Cueball on swing-set.] Woman: You know, at the peak of a big swing, you become weightless. [Thought bubble from Cueball.] [Cueball swings higher and higher. At the peak of a big swing, he shoves himself off the swing. Cueball remains hovering in the air.] Cueball: Hey guys. Come check this out.

In the opening panel of this comic, Blondie , possibly as Miss Lenhart , sees Cueball sitting on a swing set. She tells him that during his swing, he becomes weightless. Cueball then imagines that at the peak of his swing he is able to become permanently weightless, floating above the ground without any support. When on a swing or other pendulum ride , there is a moment between swinging forwards/backwards and swinging back down again when the forces of gravity, friction, air resistance, etc., bring the velocity of the swing to zero. At this moment, there is no acceleration toward the pivot of the swing (since the centripetal acceleration is proportional to the square of the speed). So the swinger experiences no centripetal force. Of course, gravity still acts on the person, but if the swing is horizontal at that point, then there is no reaction force, so for one moment, the swinger is in free-fall and experiences weightlessness . However, that weightlessness can only be maintained for a fraction of a second, so if Cueball tried this in real life, he would come crashing to the ground. In the title text, Cueball asks for a pocket fan, believing he could fly around the yard using this small device perhaps as a propeller. [Woman talking to Cueball on swing-set.] Woman: You know, at the peak of a big swing, you become weightless. [Thought bubble from Cueball.] [Cueball swings higher and higher. At the peak of a big swing, he shoves himself off the swing. Cueball remains hovering in the air.] Cueball: Hey guys. Come check this out.

Color Codes

Color Codes

https://www.xkcd.com/227

https://www.explainxkcd.com/wiki/index.php/227:_Color_Codes

[Cueball sits hunched over his desk, which is littered with objects. His Cueball-like friend holding his cell phone talks to him.] Friend: Hey, what's your cell number? Cueball: (Violet Brown Gray)— Uh, I mean, (718)-387-6962. Friend: Okay, you are putting down those resistors and going outside for a while. Cueball: That's probably a good idea.

Resistors are electronic components carrying color-coded bands indicating their value (measured in ohms ) and tolerance (e.g. 5%). Cueball has been hunched over his work for so long that, when asked for his phone number (by his Cueball-like friend), he absentmindedly reads out his phone's area code as a sequence of colors found on the aforementioned resistors (each colour corresponding to one of the ten decimal digits, in this case 718 – see Resistor color-coding ). He realizes his mistake after these first three digits and begins again using numbers to state the entire phone number. His friend points out that such a mistake means it's a good time to take a break, and Cueball concurs. It's not uncommon for readers to try calling phone numbers they see inside a book or a comic strip, just to discover what it actually goes to. Randall foresees this, and in the title text he simply tells you what the phone number is. TMBG is They Might Be Giants , an alternative rock band responsible for toe-tapping chart-topping "Birdhouse In Your Soul." At one point, they recorded individual songs on an answering machine and advertised the phone number so people could call and listen to the song on the machine. Hence, Dial-A-Song . However, the number was changed to (844)-387-6962 in 2015. TMBG has also created a website with the same function: https://dialasong.com . Resistor color codes were mentioned again in 1604: Snakes . [Cueball sits hunched over his desk, which is littered with objects. His Cueball-like friend holding his cell phone talks to him.] Friend: Hey, what's your cell number? Cueball: (Violet Brown Gray)— Uh, I mean, (718)-387-6962. Friend: Okay, you are putting down those resistors and going outside for a while. Cueball: That's probably a good idea.

Resonance

Resonance

https://www.xkcd.com/228

https://www.explainxkcd.com/wiki/index.php/228:_Resonance

[Cueball is sitting at a desk, which is vibrating.] clatter clatter [He leans back and turns to face someone sitting at another desk behind him.] Cueball: Excuse me--you're jiggling your leg up and down. It's traveling through the floor and making my desk resonate. Friend: Oh, I didn't even realize! I'll stop. [Cueball passes a sheet of paper to the friend.] Cueball: Actually, can you just shift the frequency up by 15%? I think you can get resonance with Steve's desk instead. Friend: Uh huh... Cueball: Here are the calculations. Let's coordinate and try to spill his drink.

Resonance is the tendency for an object to oscillate when energy is transferred to it at a specific set of frequencies known as harmonics of the natural frequency of the object. A simple example of this is pushing a child on a swing: by pushing the child at the right moment, more and more energy is transferred to the system and the amplitude of the oscillation grows, making the child swing higher. In this comic, the friend is jiggling his leg up and down at a harmonic of the natural frequency of Cueball 's desk. This causes Cueball's desk to vibrate more and more until objects on it start to bounce around. Rather than have the friend stop, Cueball wants him to slightly increase the frequency of the jiggling in order to spill the drink on Steve's desk (not pictured). In xkcd, no one likes Steve, as demonstrated in comics 1532 and 1672 as well as this one. However, it is hard to have a person control a subconscious movement exactly, let alone increase or decrease by exact figures. In the title text, his friend confesses the obvious fact that he couldn't control the frequency very well. (Alternatively, Randall may have made this observation himself through experimentation.) [Cueball is sitting at a desk, which is vibrating.] clatter clatter [He leans back and turns to face someone sitting at another desk behind him.] Cueball: Excuse me--you're jiggling your leg up and down. It's traveling through the floor and making my desk resonate. Friend: Oh, I didn't even realize! I'll stop. [Cueball passes a sheet of paper to the friend.] Cueball: Actually, can you just shift the frequency up by 15%? I think you can get resonance with Steve's desk instead. Friend: Uh huh... Cueball: Here are the calculations. Let's coordinate and try to spill his drink.

Graffiti

Graffiti

https://www.xkcd.com/229

https://www.explainxkcd.com/wiki/index.php/229:_Graffiti

[Cueball sits on a toilet in a bathroom. The stall sidewall next to him is covered in graffiti: "you suck," "Mike sucks cock," "CUNT," "fuck," "BITCHAS," "dane was here" struck through and "dane is a fag" written under it, a crude pictogram of a penis, and various other unreadable scribbles.] [One block of graffiti is salient:] This graffiti is fleeting human contact both of us lost, but for a moment we're lost together. I wonder who you are. I think I look for meaning in the wrong places sometimes.

The humor in this comic comes from the irony of a deep philosophical musing on the nature of individuals sharing a private space in a public place, unknown to one another and separated by time. The graffiti text is juxtaposed with more common bathroom stall scrawlings - insults, slurs, and "[Name] was here." This comic makes use of the existential idea of "finding meaning where you look for it," a recurring theme in xkcd. The caption implies that a bathroom stall isn't a place where Randall would like to find meaning in life, so he shouldn't look for it there. The title text parodies one of the archetypical pieces of graffiti: "For a good time, call [phone number]," which indicates that the person reachable at that number is available for prostitution, casual sex, and/or phone sex. However, 'good' has been replaced with 'intriguing,' implying that instead of sex, the writer is offering witty and insightful conversation. There may be a reference to this comic in 1810: Chat Systems with the chat system called Wall (bathroom) . [Cueball sits on a toilet in a bathroom. The stall sidewall next to him is covered in graffiti: "you suck," "Mike sucks cock," "CUNT," "fuck," "BITCHAS," "dane was here" struck through and "dane is a fag" written under it, a crude pictogram of a penis, and various other unreadable scribbles.] [One block of graffiti is salient:] This graffiti is fleeting human contact both of us lost, but for a moment we're lost together. I wonder who you are. I think I look for meaning in the wrong places sometimes.

Hamiltonian

Hamiltonian

https://www.xkcd.com/230

https://www.explainxkcd.com/wiki/index.php/230:_Hamiltonian

Lecturer: And therefore, based on the existence of a Hamiltonian path, we can prove that the routing algorithm gives the optimal result in all cases. Cueball: Oh my God. [Close-up of Cueball.] Offscreen: What? What is it? Cueball: A sudden rush of perspective. What am I doing here? Life is so much bigger than this! [Cueball running out of room.] Cueball: I have to go. [Cueball enters darkened room, where Megan waits by window.] [Cueball and Megan embrace...] [...and get into bed.] [A heart appears over the supine bodies.] Megan: Ohh... grip Cueball (out of frame): Wait a moment. Megan (out of frame): What is it? [Silence.] Cueball (out of frame): His proof only holds if there's a Hamiltonian cycle as well as a path! Megan (out of frame): ...excuse me? Cueball (out of frame): Paper, I need some paper. Hey, do you mind if I jot down some notes on your chest?

Cueball , presumably in class, decides that the subject of optimizing routing algorithms is not important in the larger context of life and love. However, he later realizes while in bed with Megan that there is a flaw in the proof presented, and suddenly wants to focus on the mathematics again, in a humorous reversal of his position about what is meaningful. In graph theory, a Hamiltonian path is a path that connects all the vertices (nodes) and passes through each one exactly once. (Think connect the dots with rules!) A Hamiltonian cycle is a Hamiltonian path such that the final vertex is adjacent to the initial one (intuitively, it "begins and ends with the same vertex," but recall that paths are required to only pass through each vertex once). The presenter is using graph theory to optimize a routing algorithm by solving a Hamiltonian path problem . Cueball's realization is that the proof he had followed in part actually requires a Hamiltonian cycle, not just a path, so the presenter's proof of the existence of a Hamiltonian path is insufficient to solve the problem. The title text plays on a dual interpretation of bidirectional: just as any graph cycle can be traversed in two directions, a change in perspective can be traversed in two directions (from mathematics to love, and then from love to mathematics). Lecturer: And therefore, based on the existence of a Hamiltonian path, we can prove that the routing algorithm gives the optimal result in all cases. Cueball: Oh my God. [Close-up of Cueball.] Offscreen: What? What is it? Cueball: A sudden rush of perspective. What am I doing here? Life is so much bigger than this! [Cueball running out of room.] Cueball: I have to go. [Cueball enters darkened room, where Megan waits by window.] [Cueball and Megan embrace...] [...and get into bed.] [A heart appears over the supine bodies.] Megan: Ohh... grip Cueball (out of frame): Wait a moment. Megan (out of frame): What is it? [Silence.] Cueball (out of frame): His proof only holds if there's a Hamiltonian cycle as well as a path! Megan (out of frame): ...excuse me? Cueball (out of frame): Paper, I need some paper. Hey, do you mind if I jot down some notes on your chest?

Cat Proximity

Cat Proximity

https://www.xkcd.com/231

https://www.explainxkcd.com/wiki/index.php/231:_Cat_Proximity

[A graph with the x-axis labeled, and the scale indicated from left to right:] Far Human proximity to cat Near [Two curves are drawn and labeled, first the one starting on top, which then veers downwards and crosses the other as that curve veers upwards.] Intelligence Inanity of statements [Below the graph, Cueball is seen standing at three distances from a cat that is drawn to the far right. The two first Cueballs are just standing, one below far, the other in the middle, and the last is standing close to the cat (below near) with his hands up, and he is speaking.] Cueball: You're a kitty!

This comic refers to the use of " baby talk " when speaking to pets, especially cats . A person's voice becomes falsetto and cooing , vocabulary becomes simplified, and phrases are repeated, such as "Here, kitty, kitty, kitty." The chart shows that a person's apparent intelligence decreases, and that the inanity (i.e. uselessness or emptiness) of their statements increases, the closer they get to a cat. Most people act like this when they're playing with cats or trying to call them over to them. Thankfully, being close to a cat doesn't actually cause any decrease of intelligence in normal circumstances; the graph technically refers to demonstrated intelligence rather than actual IQ levels. [ citation needed ] The title text continues Cueball's obvious statement (and thus inane/useless point made) from below the graph. In 1535: Words for Pets , Randall again mentions how people often talk strangely to their pets. [A graph with the x-axis labeled, and the scale indicated from left to right:] Far Human proximity to cat Near [Two curves are drawn and labeled, first the one starting on top, which then veers downwards and crosses the other as that curve veers upwards.] Intelligence Inanity of statements [Below the graph, Cueball is seen standing at three distances from a cat that is drawn to the far right. The two first Cueballs are just standing, one below far, the other in the middle, and the last is standing close to the cat (below near) with his hands up, and he is speaking.] Cueball: You're a kitty!

Chess Enlightenment

Chess Enlightenment

https://www.xkcd.com/232

https://www.explainxkcd.com/wiki/index.php/232:_Chess_Enlightenment

[Cueball and Megan are playing chess; Cueball is leaning forward over the chessboard.] Cueball (thinking): Why is chess so hard? Maybe the answers lie within me. Maybe I just need to let go, relax, and let my instincts and subconscious speak. [Cueball leans back and places his hands to his head.] Meditate Cueball's subconscious: Knight to G-4 [Beat panel.] Cueball: That's not even a legal move. Cueball's subconscious: Okay, hold on. How do the pawns capture, again? Cueball: Man, Obi-Wan was full of crap.

In this comic, Cueball finds his game of chess against Megan to be too difficult, and he attempts to tap his subconscious to find his next move. This is a common technique used in more physical competitions like baseball or golf, where overthinking can interfere with one's motion and thus "clearing one's mind" and relying on the subconscious is useful to overcome such mental barriers. However, chess is more a game of planning and strategy than natural movement, and the rules of chess are not ingrained into Cueball's subconscious, and so his subconscious ends up feeding him invalid moves and beginner questions concerning movement rules. Chess is a board game in which two players take turns to move a variety of different pieces representing units on a battlefield to try to capture the other player's king. Chess has a lively tournament scene and takes much practice to attain a competent level of skill in the game. Different units can move and capture in different ways; pawns can only move forward by one square unless it's their first move, in which case they can move up two squares, but they can only capture by moving diagonally unless they perform an en passant , in which they move around an opposing pawn that had moved forward two squares on the previous turn. Other pieces have different rules. Obi-Wan Kenobi is a character from the movie series Star Wars who played the mentor figure to the protagonist, Luke Skywalker . One of his pieces of advice to his mentee was to relax and listen to his subconscious in strenuous times. However, Obi-Wan gave this advice because Luke was connected to The Force, a mystical energy in the Star Wars universe that connects to the entire universe; not being a part of the Star Wars universe, Cueball is unable to tap into it. The Force does have similarities to real-life concepts used in various Eastern philosophies, but they are not typically used to play chess, for the same reasons given above. The title text refers to a scene in the chess movie Searching for Bobby Fischer , in which Sir Ben Kingsley's character dramatically sweeps the pieces off the board and instructs his student to see the pieces in his mind, which the child proceeds to do. Randall considers this impractical, presumably for similar reasons as the Obi-Wan example. [Cueball and Megan are playing chess; Cueball is leaning forward over the chessboard.] Cueball (thinking): Why is chess so hard? Maybe the answers lie within me. Maybe I just need to let go, relax, and let my instincts and subconscious speak. [Cueball leans back and places his hands to his head.] Meditate Cueball's subconscious: Knight to G-4 [Beat panel.] Cueball: That's not even a legal move. Cueball's subconscious: Okay, hold on. How do the pawns capture, again? Cueball: Man, Obi-Wan was full of crap.

A New CAPTCHA Approach

A New CAPTCHA Approach

https://www.xkcd.com/233

https://www.explainxkcd.com/wiki/index.php/233:_A_New_CAPTCHA_Approach

To complete your web registration, please prove that you're human: When Littlefoot's mother died in the original 'Land Before Time', did you feel sad? [radio button.] Yes [radio button.] No (Bots: no lying)

A CAPTCHA is a verification system to stop automatic submissions to web forms by asking the user to do something a computer program could not do, such as type a distorted word into a box. But here, the author has a new CAPTCHA, in which it references a sad event in the children's movie, The Land Before Time . It asks the subject if it felt sad. If the subject is human, then they most likely will have felt sad, so the answer will be "yes." If it's a computer program, however, it is supposed to answer "no," because computer programs cannot feel. This CAPTCHA would be extremely easy to break, however, because a computer could easily find the "yes" button and press it. However, the "trap" is that a computer program doesn't "know" that it's supposed to answer "yes," as it lacks human emotion and empathy. It is similar to the way that humans are very good at being shown simple drawings of an object or an action and being able to tell immediately what it is, while computers can't. The "no lying" instruction is ostensibly meant to patch that hole, but unfortunately, it turns out that spambots are not generally programmed with the Three Laws of Robotics. Another reason why a CAPTCHA like this won't be very practical is that some humans haven't necessarily seen the movie in the question and would be unable to know if they did feel sad or not. The title text references the Futurama episode " Jurassic Bark ". It claims that this episode is so sad that even spambots cry after seeing it. To complete your web registration, please prove that you're human: When Littlefoot's mother died in the original 'Land Before Time', did you feel sad? [radio button.] Yes [radio button.] No (Bots: no lying)

Escape Artist

Escape Artist

https://www.xkcd.com/234

https://www.explainxkcd.com/wiki/index.php/234:_Escape_Artist

[Cueball sits before a computer on a desk while another man stands behind him.] Man: I was fascinated by locks as a kid. I loved how they turned information and patterns into physical strength. Cueball: Why does my script keep dying? [Closeup on Cueball sitting at the computer.] Man: And a lock invites you to try and open it. It's the hacker instinct. Only your ignorance stands in the way. Cueball: Wait it's passing bad strings. [Returns to the two shot of both men.] Man: I admired Harry Houdini, how he could open any lock and free himself from any restraint. Cueball: Ah - Bash is parsing the spaces. Man: Sure some of it was fakery and showmanship. But I still wonder how he so consistently escaped handcuffs. Cueball: Backslashes? Man: Huh? Cueball: Never mind.

Harry Houdini (born Erik Weisz/Ehrich Weiss) was a famous escape artist, whose more famous routines included escaping straitjackets and switching places with an assistant while locked inside a box. The word "escape" also has a meaning in computer science . To "escape" something in programming means to replace a character or character sequence that would usually have a special meaning with another character sequence that doesn't have this special meaning. One common way of escaping is to have a special escape character that removes the special meaning from whatever character follows it. For instance, many programming languages enclose text strings in quotation marks (e.g. "this is a string" ). If you tried to directly put a quotation mark inside the string, the compiler would interpret it as the end of the string. To avoid this, the quotation mark is escaped with a backslash: "He said, \"Goodbye!\", and went away." The problem Cueball is having is related to the fact that the Bash shell interprets spaces as a special syntactic marker, when he actually just wants the spaces to be literal space characters. In this case, escaping the spaces with \ would force Bash to interpret his script in this way. (There is one other way the escape character is sometimes used, but we'll ignore it for the sake of explaining the comic.) The person talking to Cueball is having a separate conversation about Houdini as Cueball thinks aloud about his script issue, which results in diverging conversations. This eventually leads Cueball to suggest that Houdini might have "escaped" (freed himself from) handcuffs by "escaping" (removing the special meaning from) them with backslashes. Sometimes, escape characters need to be "nested" - the backslash character itself can be escaped as \\ to produce a literal backslash, so if, for example, one needs to produce a literal quotation mark to output to a script file, and that script file also needs to have the quotation mark escaped, one would need to type it out as \\\", which would be output as \". If I needed to actually output that \\\", one would need to type it as \\\\\\\". The number of backslashes needed grows, and can be very hard to keep track of (see 1638: Backslashes ). This behavior is a type of n-level nested quotation mentioned in the title text. This could, in practice, be very easy with syntax highlighting showing where the parser sees the string as ending, making it trivial to escape out the characters that should be escaped, e.g.: "And then he said \"Hi\"." In this example, the nested quotes could be escaped until the editor shows the uniform color of strings. An iron maiden is supposedly a medieval torture device, currently believed to have been invented for tourism purposes much later than the time period when it was said to have been used. Harry Houdini's escapes include an escape from a purported "iron maiden," although it only vaguely resembles the "medieval" torture device. [Cueball sits before a computer on a desk while another man stands behind him.] Man: I was fascinated by locks as a kid. I loved how they turned information and patterns into physical strength. Cueball: Why does my script keep dying? [Closeup on Cueball sitting at the computer.] Man: And a lock invites you to try and open it. It's the hacker instinct. Only your ignorance stands in the way. Cueball: Wait it's passing bad strings. [Returns to the two shot of both men.] Man: I admired Harry Houdini, how he could open any lock and free himself from any restraint. Cueball: Ah - Bash is parsing the spaces. Man: Sure some of it was fakery and showmanship. But I still wonder how he so consistently escaped handcuffs. Cueball: Backslashes? Man: Huh? Cueball: Never mind.

Kite

Kite

https://www.xkcd.com/235

https://www.explainxkcd.com/wiki/index.php/235:_Kite

[Cueball readies a kite.] [Cueball starts to fly the kite.] [Cueball continues to fly the kite.] [Cueball ties the kite string to a tree.] [Cueball grabs the string.] [Cueball starts to climb the string.] [A scene showing Cueball holding onto the string at a high altitude, against a colour backdrop of the ground, clouds, water, and the sky.] [Black and white again. Megan comes into view holding onto a small blimp.] Cueball (thinking): Hey, there's someone else up here. I wonder what her story is. [Megan floats to the other side of the panel.] Cueball (thinking): Maybe I should say hi. [Cueball is alone holding onto the string.] There is a fan made animated version of this comic .

This comic presents, through a surreal scenario, one of Randall's recurring themes: that it is better to take a chance and make an interesting choice . Cueball flies a kite, then fixes it to a tree and climbs its string. In real life, of course, the string would not be able to support the weight of a human. [ citation needed ] Up in the sky, Megan appears hanging on a blimp, looking at him throughout the encounter. Cueball wonders about her and considers talking to her, but he does not act. After she has gone, Cueball is alone again; nothing has changed. The title text explains the meaning of this metaphor. It is easy to regret an awkward conversation you had. In contrast, you don't regret the conversations you didn't have the nerve to start, because their cost is invisible--yet, they may have been missed opportunities, possibly a much higher cost than a simple awkward conversation. Later in the 1614: Kites title text, it turns out that other people ( Beret Guy ) can also fly with a kite. [Cueball readies a kite.] [Cueball starts to fly the kite.] [Cueball continues to fly the kite.] [Cueball ties the kite string to a tree.] [Cueball grabs the string.] [Cueball starts to climb the string.] [A scene showing Cueball holding onto the string at a high altitude, against a colour backdrop of the ground, clouds, water, and the sky.] [Black and white again. Megan comes into view holding onto a small blimp.] Cueball (thinking): Hey, there's someone else up here. I wonder what her story is. [Megan floats to the other side of the panel.] Cueball (thinking): Maybe I should say hi. [Cueball is alone holding onto the string.] There is a fan made animated version of this comic .

Collecting Double-Takes

Collecting Double-Takes

https://www.xkcd.com/236

https://www.explainxkcd.com/wiki/index.php/236:_Collecting_Double-Takes

[Cueball is standing in the middle of the produce aisle in a supermarket, holding a tube of K-Y Jelly in one hand, the other on his chin. The signs read "Bananas" "Apples" "Oranges" and "Zucchini" from left to right.] MY HOBBY: Standing in the supermarket's produce section holding a tube of K-Y Jelly, looking contemplative.

There's a fairly well-founded meme that singles looking for other singles ( mostly that being men for women, and vice-versa, but not exclusively) can make connections with others in the fresh produce sections of a supermarket. From a single lady's point of view, men who are buying such goods are more likely to be unattached, due to the traditionally skewed gender politics of who shops for what in a couple, and at the same time, the man is exhibiting good habits in not merely stocking up on ready-meals or subsisting on takeaways while living the bachelor life. By standing in a produce aisle with a tube of K-Y Jelly (which is most commonly used as a sexual lubricant) in his hand and considering what produce to buy (between bananas, apples, oranges, zucchinis, and doubtless many more off-screen), Cueball is allowing other people to believe that he either has plans to have sex with any connection he might manage to take home with him, or also he plans to use the chosen produce item to pleasure himself, probably sexually. Cueball is probably not actually planning on doing either [ citation needed ] , but he loves to see the look on people's faces; hence, he's collecting double-takes. In the title text, he says he likes to play a game of "freak out the cashier using two items." Wire coat hangers have been used to perform do-it-yourself abortions , many times with disastrous effects, such as internal hemorrhaging and the death of the woman. [Cueball is standing in the middle of the produce aisle in a supermarket, holding a tube of K-Y Jelly in one hand, the other on his chin. The signs read "Bananas" "Apples" "Oranges" and "Zucchini" from left to right.] MY HOBBY: Standing in the supermarket's produce section holding a tube of K-Y Jelly, looking contemplative.

Keyboards are Disgusting

Keyboards are Disgusting

https://www.xkcd.com/237

https://www.explainxkcd.com/wiki/index.php/237:_Keyboards_are_Disgusting

[Hairy sits at his computer, chatting with another person.] Chat: Wanna see an optical illusion? Chat: Hold your keyboard up in front of you and look at the home row. [Hairy holds the keyboard in front of him.] Chat: Now cross your eyes a little so the 'g' and 'h' overlap. Chat: Keeping focus, lift the keyboard over your head. [Hairy lifts the keyboard over his head still looking at the keyboard.] [Tiny bits of dust and skin particles fall out of the keyboard in Hairy's face.] Hairy: Eww! Chat: Ha ha

Ever cleaned a leopard? They're filthy. This comic refers to the fact that many keyboards, especially desktop keyboards, gather large amounts of crumbs and are rarely cleaned. In the comic, a person (probably Black Hat ) tricks an unsuspecting character into lifting his keyboard up so that all the crumbs fall down onto his face. By tricking the victim into de-focusing, the prankster ensures that the victim will not notice the crumbs coming out of the keyboard until it is too late, perfecting a quality online prank. The title text references the toy Etch A Sketch , in which you would draw lines using two knobs and shake the Etch A Sketch upside down to clear the screen. If you shook a gross keyboard upside down over you, you would get filth on you as well. The cleanliness (or lack thereof) of keyboards is mentioned in the title text of 1395: Power Cord . [Hairy sits at his computer, chatting with another person.] Chat: Wanna see an optical illusion? Chat: Hold your keyboard up in front of you and look at the home row. [Hairy holds the keyboard in front of him.] Chat: Now cross your eyes a little so the 'g' and 'h' overlap. Chat: Keeping focus, lift the keyboard over your head. [Hairy lifts the keyboard over his head still looking at the keyboard.] [Tiny bits of dust and skin particles fall out of the keyboard in Hairy's face.] Hairy: Eww! Chat: Ha ha

Pet Peeve 114

Pet Peeve #114

https://www.xkcd.com/238

https://www.explainxkcd.com/wiki/index.php/238:_Pet_Peeve_114

[Cueball reading a book in a chair.] Pet Peeve #114: Voice on the phone: Really? What are you doing reading ? It's Saturday night!

A pet peeve is a minor annoyance that an individual identifies as particularly annoying to them, to a greater degree than others may find it. Cueball counts his pet peeves; this is number 114. Cueball's friend calls him and finds out that he is reading a book on a Saturday night. Saturday night, or the weekend in general, is supposed to be a time for enjoying or partying with friends after five weekdays of work. But Cueball is annoyed by the fact that people are stuck with the stereotype of partying out on weekends. In his view, reading a good book is also a great way of enjoying the weekend. His annoyance is expressed in the title text. This was the first time Randall mentions his many Pet Peeves . Although the next already appeared in 283: Projection four months later, still in 2007, it is a slow growing list, but one has been added roughly every other year since then, the fifth coming towards the end of 2018 in 2080: Cohort and Age Effects . [Cueball reading a book in a chair.] Pet Peeve #114: Voice on the phone: Really? What are you doing reading ? It's Saturday night!

Blagofaire

Blagofaire

https://www.xkcd.com/239

https://www.explainxkcd.com/wiki/index.php/239:_Blagofaire

Man in Red Cape and Goggles: Hey, it worked! Cueball: What? Who are you? Man in Red Cape and Goggles: I'm from the distant future. Cueball: Wow. Hi! Man in Red Cape and Goggles: Are you a blogger? I play one of you at our festivals! Cueball: Huh? Man in Red Cape and Goggles: Like the Ren faires of your time — I do reenactments. Man in Red Cape and Goggles: We relive the days when the internet was new and free. The days of risky sharing, Slashdot, the Myspace music renaissance. The generation's finest minds meeting on comment threads, battling roving bands of trolls, and holding the great dialogues of the age! Cueball: Is that how you— Man in Red Cape and Goggles: We're fuzzy on some details. Did bloggers really wear red capes and goggles and blog from high-altitude balloons? Cueball: No! Cueball: Well, Cory Doctorow does. But nobody else.

Facts become distorted as time moves forward. What do we know about the Elizabethan times? They spoke strange English. What will 400 years from now think of the first twenty years of the Internet? Crazy people said crazy things online. Will we even say "online" 400 years from now? Won't the internet be everywhere, and everyone on it all the time in their retinal implants that being "offline" will seem absurd? Particular facts that this reenactor seems to have confused are: "Ren Faire" is short for " Renaissance Faire ", described as "an outdoor weekend gathering, usually held in the United States, open to the public and typically commercial in nature, which emulates a historic period for the amusement of its guests." While Cory Doctorow is not in this comic, the character is cosplaying him. This comic inspired several xkcd readers to give Cory Doctorow a red cape and goggles when he won the 2007 EFF Pioneer Award. Cory Doctorow's balloon is featured in 482: Height . The title Blagofaire might be an amalgamation between Blogosphere, Medieval Faire, and Blag, Randall's way of referencing his blog . The title text is probably the future cosplayer referring to the state of the future internet, indicating some organizational structure that constrains and stratifies it, and his preference for what he perceives as the wild and unfettered internet of the past. The "festival" the cosplayer references is later referenced in 771: Period Speech . Man in Red Cape and Goggles: Hey, it worked! Cueball: What? Who are you? Man in Red Cape and Goggles: I'm from the distant future. Cueball: Wow. Hi! Man in Red Cape and Goggles: Are you a blogger? I play one of you at our festivals! Cueball: Huh? Man in Red Cape and Goggles: Like the Ren faires of your time — I do reenactments. Man in Red Cape and Goggles: We relive the days when the internet was new and free. The days of risky sharing, Slashdot, the Myspace music renaissance. The generation's finest minds meeting on comment threads, battling roving bands of trolls, and holding the great dialogues of the age! Cueball: Is that how you— Man in Red Cape and Goggles: We're fuzzy on some details. Did bloggers really wear red capes and goggles and blog from high-altitude balloons? Cueball: No! Cueball: Well, Cory Doctorow does. But nobody else.

Dream Girl

Dream Girl

https://www.xkcd.com/240

https://www.explainxkcd.com/wiki/index.php/240:_Dream_Girl

[Cueball and a friend are talking.] Cueball: I had a dream that I met a girl in a dying world. [In the next frame, Cueball's words fill the entire frame.] Cueball: It was all coming apart. Hairline cracks in reality widened to yawning chasms. Everything was going dark and light all at once, and there was a sound like breaking waves rising into a piercing scream at the edge of hearing. I knew we didn't have long together. Cueball: She grabbed me and spoke a stream of numbers into my ear. Then it all went away. [A girl grabs him as cracks in the edges of the panel become tendrils and grab Cueball and the girl.] Cueball: I woke up. The memory of the apocalypse faded to mere fancy, but the numbers burned bright in my mind. I wrote them down right away. [A note reads: 42.39561 -71.13051 2007 09 23 14 38 00.] Cueball: They were coordinates. A place and a time, neither one too far away. Cueball: What else could I do? When the day came, I went to the spot and waited. Friend: ...and? Cueball: It turns out wanting something doesn't make it real.

This comic is a commentary on people who dream, daydream, and wish for things to happen, commonly in a romantic context. Cueball dreams of a girl who gives him a time and a place, and the last panel implies that he went to that place at the given time, but did not find the girl. The strip builds up hope and anticipation that this supernaturally romantic reunion will occur, but grounds the reader with the last line of the comic and the title text. The coordinates of the note lead to Reverend Thomas J. Williams Park in Cambridge, MA, USA . The time on the note, September 23, 2007, was about six months after the publishing of this comic. One hundred eighty-one days, to be exact. Notably, several hundred xkcd fans met up at that very time and place . Randall also visited the meetup, and was recorded as saying "Maybe wanting something does make it real." The idea that the frame of the comic grabs the people inside was already used in comic 82: Frame and is used again in 475: Further Boomerang Difficulties . [Cueball and a friend are talking.] Cueball: I had a dream that I met a girl in a dying world. [In the next frame, Cueball's words fill the entire frame.] Cueball: It was all coming apart. Hairline cracks in reality widened to yawning chasms. Everything was going dark and light all at once, and there was a sound like breaking waves rising into a piercing scream at the edge of hearing. I knew we didn't have long together. Cueball: She grabbed me and spoke a stream of numbers into my ear. Then it all went away. [A girl grabs him as cracks in the edges of the panel become tendrils and grab Cueball and the girl.] Cueball: I woke up. The memory of the apocalypse faded to mere fancy, but the numbers burned bright in my mind. I wrote them down right away. [A note reads: 42.39561 -71.13051 2007 09 23 14 38 00.] Cueball: They were coordinates. A place and a time, neither one too far away. Cueball: What else could I do? When the day came, I went to the spot and waited. Friend: ...and? Cueball: It turns out wanting something doesn't make it real.

Battle Room

Battle Room

https://www.xkcd.com/241

https://www.explainxkcd.com/wiki/index.php/241:_Battle_Room

[A scene is depicted from the Battle Room of the novel Ender's Game by Orson Scott Card. The boys are floating in a room with random cubes.] Dink: Sorry, Ender — seems like there were some system crashes. The battle's gotta be cut short. Ender: The lasers still work. Dink: Yeah, but the enemy's gate is down.

The book Ender's Game by Orson Scott Card is about Ender Wiggin , a boy of extraordinary intelligence, which means he is recruited to be trained to be one of the commanders of Earth's "Defense" Fleet should the Buggers invade again (future books renamed the Buggers to the Formics, to be more politically correct, since in British English, bugger is a swear word meaning to engage in anal sex, and an insult, as in "you silly bugger"). Ender is taken to a space school called Battle School. At the center of Battle School is the Battle Room, where all the training revolves (literally and figuratively) around. Ender's Game has also been discussed in later comics like 635: Locke and Demosthenes and 304: Nighttime Stories . The Battle Room is described as a hollow perfect cube. "Stars" (smaller cubes) can be pulled from the walls (without changing the shape, more stars come in to fill the space where the old ones were) and can be used as obstacles in the Battle Room, as they will remain absolutely stationary, no matter what force is exerted on them. There is no gravity in the Battle Room. Most squads entering the Battle Room keep their orientation from the hallway (gravity in the hallway dictates where "down" is in the Room). Ender realizes that because the room is a perfect cube, and that even the entrances, called "gates," are perfect squares and do not give any hint about which direction is up or down, that keeping that orientation is useless. He instructs his squad to orient so that the enemy's gate is down, a line of lateral thinking that gives his team three big advantages (smaller targets, "shielding" themselves with their own feet, and unprecedented angles of attack) and leads them to a perfect winning streak. The joke here, as made by Ender's squadmate Dink, is that the enemy's gate is "down," as in broken. A computer or a website is said to be "down" when it stops operating or is unavailable, due to a cause such as a crash, the power is cut, or it is being taken offline for maintenance. The title text suggests that the enemy's gate was sabotaged by Bean, another, possibly even smarter, friend of Ender's, for the sole reason of allowing Dink to make the joke. This reflects the developments in Ender's Shadow , the parallel story to Ender's Game , which showed that Bean was manipulating many of the events of the original book. [A scene is depicted from the Battle Room of the novel Ender's Game by Orson Scott Card. The boys are floating in a room with random cubes.] Dink: Sorry, Ender — seems like there were some system crashes. The battle's gotta be cut short. Ender: The lasers still work. Dink: Yeah, but the enemy's gate is down.

The Difference

The Difference

https://www.xkcd.com/242

https://www.explainxkcd.com/wiki/index.php/242:_The_Difference

[All the panels are circular.] [Cueball pulls a lever.] Pull [Lightning hits Cueball.] ZAP [Cueball still stands, obviously battered.] [An arrow labelled "normal person" points to a panel of Cueball thinking.] Cueball (thinking): I guess I shouldn't do that. [An arrow labelled "scientist" points to a panel of Cueball about to pull the level again.] Cueball (thinking): I wonder if that happens every time.

Cueball pulls a lever. A bolt of lightning comes down and strikes him. After being dazed for a moment, the comic then takes one of two routes; the first is that of a normal person, the second that of a scientist. In Randall 's example, the normal person would decide not to pull the lever anymore, because it seems to cause him to get struck by a bolt of lightning. But the scientist would pull the lever again to see if it was just a coincidence or if the lever actually caused the bolt of lightning. A scientist requires that results be repeatable before he accepts the results. The title text refers to the scientist's method of pulling the lever again and again, trying to understand how the machine works, as opposed to the normal person, just avoiding pain. This could be a nod towards how scientists sometimes go to extreme measures for knowledge. For a different view on the topic of repetition in experimentation, see 1657: Insanity . [All the panels are circular.] [Cueball pulls a lever.] Pull [Lightning hits Cueball.] ZAP [Cueball still stands, obviously battered.] [An arrow labelled "normal person" points to a panel of Cueball thinking.] Cueball (thinking): I guess I shouldn't do that. [An arrow labelled "scientist" points to a panel of Cueball about to pull the level again.] Cueball (thinking): I wonder if that happens every time.

Appropriate Term

Appropriate Term

https://www.xkcd.com/243

https://www.explainxkcd.com/wiki/index.php/243:_Appropriate_Term

[A diagram of a TrackPoint pointer on a keyboard, under which is a continuous line labeled "Tone of Conversation-Formal to Informal." There are four boxes under this line.] How to refer to the pointer thing on laptop keyboards: Very formal: TrackPoint™-style pointer Formal: Nub Informal: Nipple mouse Very informal: Clit mouse

This is a simple comic offering increasingly not-safe-for-work names for a laptop's pointing device . This stick was an alternative to a mouse, but has largely been supplanted by the touchpad. "TrackPoint" is the trademarked term used by IBM (and later Lenovo) for the pointing stick implemented on ThinkPad laptops. They are usually colored red, as in the comic. Other manufacturers have alternative names for their implementations, and typically use diferent colors. It is obviously the most formal of the four names. The more informal two are nub and nipple mouse (referencing breasts), with the last, most informal being clit mouse, a reference to clitoris (part of the female genitalia). The title text notes that Randall prefers pointing sticks to touchpads. [A diagram of a TrackPoint pointer on a keyboard, under which is a continuous line labeled "Tone of Conversation-Formal to Informal." There are four boxes under this line.] How to refer to the pointer thing on laptop keyboards: Very formal: TrackPoint™-style pointer Formal: Nub Informal: Nipple mouse Very informal: Clit mouse

Tabletop Roleplaying

Tabletop Roleplaying

https://www.xkcd.com/244

https://www.explainxkcd.com/wiki/index.php/244:_Tabletop_Roleplaying

[Four people sit around a table. Megan has an open gamebook in front of her.] Megan: Your party enters the tavern. Cueball: I gather everyone around a table. I have the elves start whittling dice and get out some parchment for character sheets. Megan: Hey, no recursing.

Four people are playing a role-playing game . Megan is the game master (GM), describing the events of the adventure and what happens. The other people control imaginary characters in the game. Cueball attempts to have his character lead other characters in the imaginary construction of dice and gaming sheets. This would allow his character to become the GM of a new game inside the game they're currently playing, effectively taking control of the game away from Megan (at least temporarily). To "recurse" refers to recursion , a concept of computer programming where a piece of code calls itself, essentially making the code run multiple times "within" itself. This may be the simplest way to implement an otherwise long and complicated action. (For example, a folder may contain files inside, but also more folders inside. Asking a computer to 'search through everything' in a folder may involve first checking the files in that folder, and then checking the folders in that folder and 'searching through everything' again in those folders. The single command to 'search through everything' may cause numerous additional 'search through everything' commands to trigger on increasingly nested folders, stopping only once a folder(s) with only files inside (and no folders inside) is found.) It should be noted that Megan, the current GM, has multiple ways of dealing with this scene to prevent Cueball from attempting to take control of the game. She could simply allude to the success or failure of the recursive game and "skip to the next scene." She could also allow the roleplaying to continue more literally, with crafting checks determining the quality of the miniatures and a gambling check determining the outcome of the in-universe RPG session. Finally, she could simply have the party's plans be interrupted by some sort of threat , or just drop huge rocks on the party . The title text refers to a pair of fictional rings. Anything passing through one gets teleported instantly to the other, as if the two rings were next to each other. There's an old gamer theory that, if you drop one of the rings in the ocean, water will naturally pass through it and out the other ring, potentially draining the entire ocean, or at least creating a perpetual seawater fountain out of the other ring. And if you teleported one ring directly to the bottom of the ocean, the amount of pressure pushing the water through would cause a gigantic, never-ending torrent, obliterating anything placed in its path. That idea is drawn out in 969: Delta-P . A similar concept is addressed in What If? 53, "Drain the Oceans , where a reader asked "How quickly would the oceans drain if a circular portal 10 meters in radius leading into space was created at the bottom of Challenger Deep, the deepest spot in the ocean? How would the Earth change as the water is being drained?" . This question may have been inspired by the mention of throwing teleport rings into the ocean in this cartoon. The rings themselves are most likely inspired by the "Ring Gates" item from the Dungeons and Dragons 3.5 Dungeon Master's Guide (the most recent edition of Dungeons and Dragons at the time this comic was published), which had a similar function. However, a key thing to note is that the rings only allow 100 lbs of material to pass through them each day, meaning that your geyser would only erupt every 24 hours (though this may still qualify as an "interesting result"). [Four people sit around a table. Megan has an open gamebook in front of her.] Megan: Your party enters the tavern. Cueball: I gather everyone around a table. I have the elves start whittling dice and get out some parchment for character sheets. Megan: Hey, no recursing.

Floor Tiles

Floor Tiles

https://www.xkcd.com/245

https://www.explainxkcd.com/wiki/index.php/245:_Floor_Tiles

[Two characters walk on a floor tiled in black and white.] Friend: Why are you walking funny? [Second panel consists of Cueball's thought cloud in which he points to an easel mounted diagram of the floor tile pattern.] Cueball, thinking: Well, my instinct is to step only on black tiles, but they're too far apart. So I'm letting myself walk on the tiles directly in line with the black ones, but that means that when we walk diagonally, I have to step in a pattern where... [Returns to situation in first panel.] Cueball: I'm not walking funny.

Cueball is walking according to a certain pattern of floor tiles, which makes sense to him in his head (the same pattern was first introduced in 207: What xkcd Means ). But as his friend asks him why he is walking funny, he realizes that the algorithm he is using for walking on floor tiles would be so tedious and time-consuming to explain to his friend that he decides instead to simply defend himself and say that he isn't walking funny, this being far simpler than trying to show his friend exactly how his logic works. Alternatively, he is too embarrassed to explain his algorithm. Cueball has imagined a complex diagram in his head. However, the diagram does not accurately reflect the floor, as the two main rows with black tiles in the foreground are only separated by one row of white tiles instead of two. This could possibly be an error on Randall's part, as the tiles in the background follow the pattern shown in the imagined diagram. The title text refers to a common compulsion that leads people to place their feet either exactly between sidewalk cracks or directly on top of them while walking. Indeed, if the cracks are out of sync with one's natural stride, this will cause some people to "walk funny" as they stumble to correct their foot placement. [Two characters walk on a floor tiled in black and white.] Friend: Why are you walking funny? [Second panel consists of Cueball's thought cloud in which he points to an easel mounted diagram of the floor tile pattern.] Cueball, thinking: Well, my instinct is to step only on black tiles, but they're too far apart. So I'm letting myself walk on the tiles directly in line with the black ones, but that means that when we walk diagonally, I have to step in a pattern where... [Returns to situation in first panel.] Cueball: I'm not walking funny.

Labyrinth Puzzle

Labyrinth Puzzle

https://www.xkcd.com/246

https://www.explainxkcd.com/wiki/index.php/246:_Labyrinth_Puzzle

[Three guards with spears stand in front of three doors. Black Hat and Cueball stand in front of the guards.] Black Hat: And over here we have the labyrinth guards. One always lies, one always tells the truth, and one stabs people who ask tricky questions.

This comic alludes to a famous Knights and Knaves logic puzzle, and specifically to the version featured in the Jim Henson movie Labyrinth , with two doors and two guards. One guard always lies, and the other always tells the truth. One of the doors leads to freedom, and you can only ask one guard one question. The solutions to this riddle (and there are several, though all are somewhat similar) involve a tricky question indeed. If you want to give the original puzzle a try for yourself, don't read the spoilers below. Notably enough, both solutions require that the guards be aware of each other's practice regarding truth and lies, which is not stated in the riddle itself. There's another unspoken rule: that the lie is either a yes or a no. If you asked the liar something, he could lie and say, "I don't know," which would leave you with nothing. Black Hat added a third guard here who would stab his spear to Cueball on every tricky question. But even if the questions from before are not tricky enough to get stabbed, there would be no helpful answer. And if Cueball asks one of the other guards, the answers can't help to find the correct door. The only saving grace is that Black Hat has seemingly forgotten to impose the limit of a single question, but depending on how stab-happy the third guard is or is not, this may not be enough. The title text presents a typical behavior of Black Hat — no door in fact does lead out of this labyrinth. (Neither door is correct in Labyrinth , either; people paying close attention will note that since the guards themselves explain the premise, even though one of them supposedly always lies, they can't possibly be taken at face value.) [Three guards with spears stand in front of three doors. Black Hat and Cueball stand in front of the guards.] Black Hat: And over here we have the labyrinth guards. One always lies, one always tells the truth, and one stabs people who ask tricky questions.

Factoring the Time

Factoring the Time

https://www.xkcd.com/247

https://www.explainxkcd.com/wiki/index.php/247:_Factoring_the_Time

[One man is sitting at a computer. Cueball sits at a separate desk. There is a clock that reads 2:53.] Cueball: 253 is 11x23 Man at computer: What? Cueball: I'm factoring the time. [Zoomed in on Cueball, who explains himself.] Cueball: I have nothing to do, so I'm trying to calculate the prime factors of the time each minute before it changes. Cueball: It was easy when I started at 1:00, but with each hour the number gets bigger Cueball: I wonder how long I can keep up. [Zoomed back out on the man and Cueball. The man at the desk reaches back and touches the clock.] BEEP [Clock now reads 14:53.] Cueball: Hey! Man at computer: Think fast.

In this comic, Cueball is bored, so he is calculating the prime factors of the time shown on the clock. Cueball has been doing this for almost two hours (from 1:00 pm to 2:53 pm). The number 2 is the smallest prime but is not a factor of 253, which is an odd number. The smallest prime factor of 253 is 11, which makes the other factor 23. His co-worker decides to mess with Cueball, so he switches the clock from 12-hour time (2:53 pm) to 24-hour time (14:53). This makes factorization more difficult, as the time now shown is a four digit number rather than a three digit number. The number 1,453 is actually a prime number, and so has no factors but one and itself. Cueball has less than one minute to determine this, which is nearly impossible to do without practice. In this time, Cueball would have to calculate if 1,453 is divisible by all primes between 2 and the square root of 1,453, which are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, and 37. However, there are tricks to help you do this more quickly than doing long divisions . In the title text, Randall claims that he applies the same challenge to highway location markers . At highway speeds (60+ mph), they would show up at least once per minute. Combined with the need to also concentrate on driving, factorizing numbers in the allowed time becomes much more difficult despite the lower numbers on the markers. Also, paying attention to the road markers instead of the road itself would be quite terrifying, and could cause a car crash at more than 60 mph. Obviously, this would be bad. [ citation needed ] An additional challenge would be to change the mile markers to kilometer markers (because as with the clock format, the latter is more common outside of the USA). That would result in the marker being a 1.6 times larger number, and thus harder to factor. Of course, factoring is now a secondary problem, as markers would appear 1.6 times as frequently. [One man is sitting at a computer. Cueball sits at a separate desk. There is a clock that reads 2:53.] Cueball: 253 is 11x23 Man at computer: What? Cueball: I'm factoring the time. [Zoomed in on Cueball, who explains himself.] Cueball: I have nothing to do, so I'm trying to calculate the prime factors of the time each minute before it changes. Cueball: It was easy when I started at 1:00, but with each hour the number gets bigger Cueball: I wonder how long I can keep up. [Zoomed back out on the man and Cueball. The man at the desk reaches back and touches the clock.] BEEP [Clock now reads 14:53.] Cueball: Hey! Man at computer: Think fast.

Hypotheticals

Hypotheticals

https://www.xkcd.com/248

https://www.explainxkcd.com/wiki/index.php/248:_Hypotheticals

[Cueball is holding up his hand towards Beret Guy, who talks to him. From Beret Guy's head go three bubbles to a big thought bubble, where the next part of the comic takes place.] Beret Guy: What if I had some ice cream? Wouldn't that be awesome? Cueball: No, stop- [The comic continues inside Beret Guy's thought bubble. The two characters have switched places, and Beret Guy is now eating from an ice cream cone. Cueball is holding his hand to his chin, and from his head go four bubbles to a thought bubble in the lower right corner, where the last part of the comic takes place.] Cueball: Great, you've trapped us in a hypothetical situation! Beret Guy: Mmm, ice cream. Cueball: Maybe if I had a knife I could cut our way free... [Inside Cueball's thought bubble, Beret Guy continues to eat his ice cream, but Cueball has cut a hole through the last thought bubble with a knife and is handing it to the Cueball who thinks about this]. Beret Guy: Mmm, ice cream! Cueball: Here, take this one.

The comic is, in short, a new take on the common comedy trope in which characters in a thought bubble will sometimes look out of the bubble and talk directly to the person thinking it, another person nearby, or even the viewer. In this comic, however, it features Cueball and Beret Guy in a conversation together, in which Beret Guy talks of a hypothetical situation by imagining he had ice cream. This then, to Cueball's dismay, creates a hypothetical situation in which Beret Guy has ice cream, which he promptly begins to eat. Cueball then creates a hypothetical situation in which his hypothetical self has a knife to 'cut' out of the thought. He then gives this knife to Cueball, who supposedly will use it to cut out of his hypothetical situation. The title text puts the comic into context, noting the unlikely possibility — and your most likely surprised reaction — if a person in a hypothetical situation you'd involuntarily created managed to break out of it and suddenly appear in your room. Or it could be understood the other way, that a person you have forced into your hypothetical situation breaks free from it, and disappears from your room. Also, it points out that the situation is in fact a hypothetical situation itself, creating some irony. Another "thought bubble comic" can be seen in 429: Fantasy , and the topic of people escaping from hypothetical situations appears again in 1582: Picture a Grassy Field . [Cueball is holding up his hand towards Beret Guy, who talks to him. From Beret Guy's head go three bubbles to a big thought bubble, where the next part of the comic takes place.] Beret Guy: What if I had some ice cream? Wouldn't that be awesome? Cueball: No, stop- [The comic continues inside Beret Guy's thought bubble. The two characters have switched places, and Beret Guy is now eating from an ice cream cone. Cueball is holding his hand to his chin, and from his head go four bubbles to a thought bubble in the lower right corner, where the last part of the comic takes place.] Cueball: Great, you've trapped us in a hypothetical situation! Beret Guy: Mmm, ice cream. Cueball: Maybe if I had a knife I could cut our way free... [Inside Cueball's thought bubble, Beret Guy continues to eat his ice cream, but Cueball has cut a hole through the last thought bubble with a knife and is handing it to the Cueball who thinks about this]. Beret Guy: Mmm, ice cream! Cueball: Here, take this one.

Chess Photo

Chess Photo

https://www.xkcd.com/249

https://www.explainxkcd.com/wiki/index.php/249:_Chess_Photo

[Cueball sits at a desk with glue, chess pieces, and a chessboard, while his Cueball-like friend looks over his shoulder.] Friend: What are you doing? Cueball: Gluing down chess pieces. Friend: Why? Cueball: Because there's a picture I've always wanted... I'll need your coat to sneak this onto the ride. [A photograph of a roller coaster ride with Cueball sitting in the first car, chin in hand, thinking over the chessboard and the rest of the people screaming with their hands up. The photograph has "Mega Coaster 3000 souvenir photo" written on the bottom margin.]

A roller coaster is a kind of thrill ride where a small train carries people through a number of twists, turns, and hills at a high speed to the occupants' great delight. Such rides are popular at amusement parks, where people have to wait in long lines to get on a ride that can last less than two minutes. Many amusement parks have a spot where they take souvenir pictures as you are experiencing the ride. After you get off the ride, you can buy one picture or a set of pictures to commemorate riding the roller coaster. These pictures usually have people with their hands up, yelling and screaming. Wind may be going through their hair as they pass through the air at high speeds. Cueball is subverting the usual 'souvenir picture pose' by gluing chess pieces to a board and then staring at the board when the picture is taken. He stands out in the picture as a calm person studiously studying a chess problem while everyone else yelps and whoops with excitement. The title text refers to blindfold chess, which doesn't require any actual blindfold, it's just called that because the two players don't need a board and just communicate their moves. This would of course be impossible to photograph. This might also be a pun on actually not being able to see while playing chess, as the Aerosmith ride (officially the Rock 'n' Roller Coaster Starring Aerosmith ) is indoors and not lit up, making it extremely hard to see anything while on the ride. [Cueball sits at a desk with glue, chess pieces, and a chessboard, while his Cueball-like friend looks over his shoulder.] Friend: What are you doing? Cueball: Gluing down chess pieces. Friend: Why? Cueball: Because there's a picture I've always wanted... I'll need your coat to sneak this onto the ride. [A photograph of a roller coaster ride with Cueball sitting in the first car, chin in hand, thinking over the chessboard and the rest of the people screaming with their hands up. The photograph has "Mega Coaster 3000 souvenir photo" written on the bottom margin.]

Snopes

Snopes

https://www.xkcd.com/250

https://www.explainxkcd.com/wiki/index.php/250:_Snopes

[Two Cueballs sit at a table across from each other, typing on their laptops.] Cueball: Another urban legend? You should check out Snopes before sending me this stuff. Friend: Oops; yeah. Cueball: Man, Snopes is really great--independent fact-checkers trawling our collective discourse, filtering out misinformation. [The Cueballs are still sitting at the table across from each other, looking at each other.] Friend: Yeah, but they have their dark side. The couple that runs snopes.com also runs a network of spam servers that start many of those forwarded stories in the first place, ensuring they'll always have business. [Cueball on the left is typing on his laptop, while the second Cueball is sitting, stunned.] Cueball: That's absurd. Plus, it's definitely not true--it was debunked by... Friend: Yes? Cueball: ...Oh my God. Snopes is also mentioned in the much later comic 1081: Argument Victory in a much more positive light.

Snopes is a popular website for checking the validity of urban legends . Here, one Cueball asks the other to check before sending him urban legends. Cueball replies with another urban legend saying that Snopes, the website the first Cueball asks him to check, uses spam to keep their audience. Naturally, it didn't take long for an urban legend to suggest that the proprietors of Snopes also direct a spam operation to create more urban legends and disseminate them, just so they'll continue to have an audience. One of the Cueballs tries to come to Snopes' defense, only to realize that the debunking was done by Snopes itself, creating a circular, invalid argument. The title text suggests that MythBusters , another group that debunks myths, also participate in the practice of spreading misinformation for the opportunity to test it. Indeed, the show has occasionally been accused of spending undue attention on unnecessary filler "myths" just for the sake of filling out the season. [Two Cueballs sit at a table across from each other, typing on their laptops.] Cueball: Another urban legend? You should check out Snopes before sending me this stuff. Friend: Oops; yeah. Cueball: Man, Snopes is really great--independent fact-checkers trawling our collective discourse, filtering out misinformation. [The Cueballs are still sitting at the table across from each other, looking at each other.] Friend: Yeah, but they have their dark side. The couple that runs snopes.com also runs a network of spam servers that start many of those forwarded stories in the first place, ensuring they'll always have business. [Cueball on the left is typing on his laptop, while the second Cueball is sitting, stunned.] Cueball: That's absurd. Plus, it's definitely not true--it was debunked by... Friend: Yes? Cueball: ...Oh my God. Snopes is also mentioned in the much later comic 1081: Argument Victory in a much more positive light.

CD Tray Fight

CD Tray Fight

https://www.xkcd.com/251

https://www.explainxkcd.com/wiki/index.php/251:_CD_Tray_Fight

[Cueball is standing, holding a CD tray that is half-in his computer. There are other CDs on the floor.] Cueball: Hey. Hey! Stop retracting my CD! I feel uncomfortable when my computer physically struggles with me. Sure, I can overpower it now , but it feels like a few short steps from here to the robot war.

This comic refers to the behavior of a tray loading optical disc drive of a desktop computer. When the tray is opened and the user is reaching for the disc, a process or task on the computer can, at that exact inopportune time, request that the disc drive close its tray. Alternatively, accidentally bumping the open tray may engage the auto-close feature, resulting in the same scenario. This results in a sort of "tug of war" between the user who is trying to remove the disc and the CD drive trying to retract, and it is this tug of war that worries Cueball (or, more likely, Randall) that the "Robot War" is impending. The title text, however, points out that this fear is irrational, not because we'll always be able to win the tug of war (even if the computer reprograms itself to ignore our pull, we are physically stronger than the retraction mechanism) or because the act is ultimately pointless (it's an indignant protest at best), but because any robot war will, necessarily, have to start in "the network" to get any traction. A Robot War is a recurring theme in science fiction where humans develop robots that become self-aware and start a war against humanity. A well-known example of this theme is found in the Terminator franchise where, as the title text suggests, a military computer network ( Skynet ) becomes self-aware and starts a world war to kill all humans. This event is also parodied in 1046: Skynet , but with Skynet failing due to semantic satiation . [Cueball is standing, holding a CD tray that is half-in his computer. There are other CDs on the floor.] Cueball: Hey. Hey! Stop retracting my CD! I feel uncomfortable when my computer physically struggles with me. Sure, I can overpower it now , but it feels like a few short steps from here to the robot war.

Escalators

Escalators

https://www.xkcd.com/252

https://www.explainxkcd.com/wiki/index.php/252:_Escalators

[A graph with y-axis titled "Urge to try running up the down escalator," with "weak" by the bottom and "strong" by the top. The x-axis has every two years labeled and every year signified by a smaller mark, which stops at 24. A red line with "What I was supposed to feel" with points at every line rises, peaks at 7 years old, then falls "tangent graph" shaped until the end. Along this line are shown various Cueball-like figures at 12, 14, 20, and 24. A second red line runs "What I've actually felt," which stays consistently high.] Escalators were also the subject of the later comic 954: Chin-Up Bar , a rather more sinister take on those funny devices.

This comic shows two simple line graphs on the same chart. One shows society's expectations, the other what Randall actually felt. The visual joke is that the societal expectation graph is treated like an actual down-moving escalator, with people on it. An escalator is a continuously moving mechanized stairway that travels in a particular direction, either up or down. Traditionally, people stop walking when riding the escalator and simply stand (perhaps holding the hand-rail) until they reach the destination and then step off. However, if you are in a hurry or impatient, it is possible to also climb the stairs manually, increasing your effective speed of ascent or descent. Young children are typically fascinated by escalators, and they will often want to run up and down them just for fun. A variation is to travel the escalators in the opposite to the intended direction. Running up the down escalator is type of physical challenge, especially for younger children, as they are fighting gravity and the downward motion of the escalator to reach the top. If they pause or cannot keep up sufficient speed, the escalator will impersonally return them to their starting position. The curved graph on the chart shows how the urge to run up the down escalator is expected to peak at about age 7 and then decline steeply as you approach adulthood, although never quite reaching zero. For Randall (it seems to be Randall who is speaking), the urge has not diminished in any way, and it even seems to be showing an upward trend as the graph approaches 24 years of age. He does not appear to have acted upon this urge very often - in fact he claims only once. The title text refers to the Slinky toy, a coiled spring that is designed to go down stairs by itself in an amusing manner. Since the Slinky is moving with the flow , its effective speed is increased. A normal Slinky is very small and would not be able to halt an average human being through its inertia, but it could tangle up in their feet or otherwise trip them up, and it would at least be a surprising encounter. [A graph with y-axis titled "Urge to try running up the down escalator," with "weak" by the bottom and "strong" by the top. The x-axis has every two years labeled and every year signified by a smaller mark, which stops at 24. A red line with "What I was supposed to feel" with points at every line rises, peaks at 7 years old, then falls "tangent graph" shaped until the end. Along this line are shown various Cueball-like figures at 12, 14, 20, and 24. A second red line runs "What I've actually felt," which stays consistently high.] Escalators were also the subject of the later comic 954: Chin-Up Bar , a rather more sinister take on those funny devices.

Highway Engineer Pranks

Highway Engineer Pranks

https://www.xkcd.com/253

https://www.explainxkcd.com/wiki/index.php/253:_Highway_Engineer_Pranks

[Each panel depicts a highway intersection.] The Inescapable Cloverleaf: [Roads lead onto the rings for each leaf, but then are trapped in the circles. Minor roads also allow travel between the rings.] The Zero-Choice Interchange: [On- and off-ramps exist, but they lead back to the same lane they disconnected from.] The Rotary Supercollider: [The roads lead into a traffic circle, and then a loop reverses the direction of flow so all the roads run into each other.]

Some classical but inaccurate interchanges are shown. In general, these interchanges are designed to allow the traffic to flow without directly crossing any other traffic stream. But here we can see some different approaches: In the title text, Boston is mentioned, a slightly more complicated prank in itself. A common fiction is that the streets evolved from old cowpaths, but in the 17th century, they avoided swamps and marshes and followed shorelines before the original peninsula comprising the city was expanded with landfill in the 19th century. Boston's road infrastructure in general lacks a street grid like most other US cities have. On top of that, roads change names and lose and add lanes seemingly at random. Randall himself lives in Boston. Highway engineers were also the subject of 781: Ahead Stop and 1726: Unicode . [Each panel depicts a highway intersection.] The Inescapable Cloverleaf: [Roads lead onto the rings for each leaf, but then are trapped in the circles. Minor roads also allow travel between the rings.] The Zero-Choice Interchange: [On- and off-ramps exist, but they lead back to the same lane they disconnected from.] The Rotary Supercollider: [The roads lead into a traffic circle, and then a loop reverses the direction of flow so all the roads run into each other.]

Comic Fragment

Comic Fragment

https://www.xkcd.com/254

https://www.explainxkcd.com/wiki/index.php/254:_Comic_Fragment

Editor's note: Mr. Munroe has been missing for several days. We have recieved no submissions from him for some time, but we found this single panel on his desk in a folder labeled 'MY BEST IDEA EVER'. It is clearly part of a work in progress, but we have decided to post it in lieu of a complete comic. [Single panel illustration in color with one small panel embedded within, showing a zoomed-in version of Janeane Garafolo on a motorcycle. The background is a gray landscape beneath a falling space station, a large volcano with smoke rising the only discernible feature of the landscape below.] As the damaged space station fell deeper into the atmosphere and started to break up around her, Janeane Garofalo tightened her grip on the motorcycle. The volcano was looming ahead, and her tranquilizer pistol only had six darts left - barely enough to bring down even one Tyrannosaur.

In this comic, Randall has gone missing from the office, and his 'editors' have found only this panel from an unfinished project (of which he has labeled 'best idea ever'). The panel depicts an amalgam of science fiction disasters. Janeane Garofalo is an actress and comedian associated with strong feminist roles and opinions. She is an unlikely choice for an action hero, but she has fringe appeal. It should be noted that in the panel it is Janeane Garofalo herself on the motorcycle, not a character played by Janeane Garofalo, meaning she is the character. Randall is parodying a mode of self-indulgence common among artists and writers, particularly those who have been prolific and have gained mass appeal. A writer might have a project he thinks of as his "best idea ever," but upon examination, it is just a mish-mash of ideas the writer thinks are cool, which don't add up to a coherent story. This type of project is self-indulgent because it allows the writer to feel like he's exercising creative impulses he can't use in his regular work, even though the actual project has little artistic merit and is unlikely to appeal to a popular audience. In this strip, Randall winks at a lot of the hallmarks of this sort of "project:" Some of the ideas (dinosaurs, spacecraft) are derivative of Randall's prior work; others (volcanoes, Janeane Garofalo) are not. It is telling, though, that the closeup inset of the woman on the motorcycle, while referred to as Janeane Garofalo in the text, looks an awful lot like Megan . The title text is written from the 'editors' perspective, expressing their extreme puzzlement - outshone only by Ms. Garofalo's confusion. Later on, in December 2007, Randall Munroe suggested in a speech at Google that a motivation to draw this comic was to put an end to reenactments of his comics (such as the Richard Stallman and Cory Doctorow comics, which inspired real-life happenings )... or challenge anyone to reenact such a complex one: I've been doing these comics, and people have a habit of acting out the comics. I first — I did a comic about Cory Doctorow; you know, he wears red cape and goggles when he blogs and a week or so later, he was given an award. And he went up on the stage; they presented him with a red cape and goggles. I have done a comic little before that about Richard Stallman suggesting that he sleeps with the katana, you know, just in case. And, sure enough, they sent him, some fans pitched in together and sent him a katana. He had never heard of the comic. He was very confused. And I decided, okay, this is going to get out of hand. So, shortly after all that, I did a comic about Janeane Garofalo jumping a motorcycle off of the International Space Station as it crashes over an island with a volcanic eruption and Tyrannosaurus. And I said, okay, if someone can make that happen, but until they do that... Editor's note: Mr. Munroe has been missing for several days. We have recieved no submissions from him for some time, but we found this single panel on his desk in a folder labeled 'MY BEST IDEA EVER'. It is clearly part of a work in progress, but we have decided to post it in lieu of a complete comic. [Single panel illustration in color with one small panel embedded within, showing a zoomed-in version of Janeane Garafolo on a motorcycle. The background is a gray landscape beneath a falling space station, a large volcano with smoke rising the only discernible feature of the landscape below.] As the damaged space station fell deeper into the atmosphere and started to break up around her, Janeane Garofalo tightened her grip on the motorcycle. The volcano was looming ahead, and her tranquilizer pistol only had six darts left - barely enough to bring down even one Tyrannosaur.

Subjectivity

Subjectivity

https://www.xkcd.com/255

https://www.explainxkcd.com/wiki/index.php/255:_Subjectivity

[A tall slide, seen from the ground.] When I was a kid, my school playground had a really tall slide that always made me nervous. [A tall slide, seen from the side.] We moved away, but the slide stuck in my memory, becoming a skyscraping monster. [A car and a sign pointing to school zone.] Years later, I was passing through my old town and remembered the playground. I drove to the school to see the slide that my inner six-year-old thought was so towering. [A huge slide, Cueball beside it.] AND IT WAS HUGE! I KNEW IT!

Parodying the experience of finding that things you saw as a child are much smaller than you'd perceived them to be, Cueball is convinced that this will be the case with his childhood slide, only to find that it is indeed quite large. (As a child, it's roughly nine times his height; as an adult, it's only about triple.) The title text references Aslan , a character from The Chronicles of Narnia . Aslan is often regarded as a Christ figure, but since Narnia is a children's series, many readers don't realize this until long after they've read the books – another instance of how perspective changes with age, and of the comic's title, "subjectivity." [A tall slide, seen from the ground.] When I was a kid, my school playground had a really tall slide that always made me nervous. [A tall slide, seen from the side.] We moved away, but the slide stuck in my memory, becoming a skyscraping monster. [A car and a sign pointing to school zone.] Years later, I was passing through my old town and remembered the playground. I drove to the school to see the slide that my inner six-year-old thought was so towering. [A huge slide, Cueball beside it.] AND IT WAS HUGE! I KNEW IT!

Online Communities

Online Communities

https://www.xkcd.com/256

https://www.explainxkcd.com/wiki/index.php/256:_Online_Communities

[Hand-drawn fantasy style map with land and sea areas representing populations of online communities. Each area or item is labeled.] Map of Online Communities and related points of interest Geographic area represents estimated size of membership [Land Area Labels:] The Icy North (Yahoo, Windows Live), AOL, Chat Rooms Reunion dot com, Classmates dot com, E-harmony, Friendster, Faceparty, Chasm, Qwghlm, Yahoo Games, Mountains of Web 1.0, The Lonely Island, MySpace, Attractive MySpace Pages, The Series of Tubes, Myspace Bands, WOW, Lineage, Second Life, Third Life, UO, EQ, FFXI, 2channel, 4chan, LJ, Xanga, Orkut, Cyworld, Blurty, OK Cupid, Facebook, Piczo, The Compass-Rose-Shaped Island, Practicals (Noob) Focus on Real Life (IRL) Focus on Web (.com) Intellectuals (π) Broadcaster, The Bit Torrent, Flickr, Last.fm, DeviantArt, Isle of Slash, Numa, Digg, Fark, Reddit, Something Awful, Your Base, Soviet Russia, /. [Slashdot], Spaaarta (YTMND), StumbleUpon, Del.icio.us, The Blogipelago, Sulawesi, Xu Jinglei, Post Secret, Technocrati, [Hard to read label: Probably JWB, TWB, or TMZ] BoingBoing, Huffington Post, Gays of Web 2.0, The Wikipedia project, MIT, Engadget, Gizmodo, Usenet, MAKE Blog, IRC Isles, Sourceforge. [Sea Area Labels:] NOOB Sea, Gulf of YouTube, Bay of Angst, Sea of Culture, Ocean of Subculture, P2P Shoals, Straits of Web 2.0, Here Be Anthropomorphic Dragons, Bay of Trolls, Viral Straits, Sea of Memes, The Wet Sea Item Labels: Shipwreck of the SS Howard Dean, Cory Doctrow's Balloon, Stallman's airship, Google's volcano fortress (Not a complete survey. Sizes based on the best figures I could find but involved some guesswork. Do not use for navigation.) Spring 2007

Note: This comic dates from Spring 2007. The internet has changed a lot since that time. This is Randall's first map of online communities, with a successor (showing some zoomed-in highlights of the map) at 802: Online Communities 2 . As Randall says on the map, the area of each "country" is roughly proportional to its membership, at least in 2007. Geographic location means a bit more, however, as the Compass-Rose-Shaped Island points out. North-south corresponds to a spectrum from practical to intellectual, and east-west corresponds to one from web-focused to real-life-focused. The map also bears a slight resemblance to South East Asia . Randall likes to draw maps in a manner like this. Each "country" is represented by size and related points of interest. We also have a "Sea of Memes" and a small "Straits of WEB 2.0." This is a joke located near the middle of the map, that nonetheless serves to organize the illustration. A Compass Rose —the name for the multi-pointed star that shows where North is on the map— appears on most maps; however, here, it's actually land that just coincidentally looks like a compass rose. The "points" of the island do, however, roughly organize the map. Left is "Focus on Real Life," labelled "IRL," an abbreviation for "In Real Life." Right is "Focus on Web," labelled ".com." Up is "Practicals," labelled "N," as in "North," but with small letters making it spell "Noob," slang for a "Newbie" or "New user" — a person less experienced with the internet, as many of the sites to the top of the map are ones infamous for having large numbers of largely computer-illiterate people. Down is "Intellectuals," labelled "π," an important constant in mathematics approximately equal to 3.14159265358979323846264338. These are communities that were once major players, but now in a much reduced role. While some are still fairly large, they're somewhat relics of older times, hence the "Mountains of Web 1.0" that run through them — Web 1.0 is the first major generation of websites. These are sites mainly used to communicate with friends, such as Facebook and Myspace. The first large one was Friendster , but this has largely become a social gaming site primarily used in Southeast Asia, as discussed in The Icy North, above. Other social media sites listed are: This is a portmanteau of blog and archipelago. Sulawesi is a real island in the Indonesian archipelago, implying that this region's similarity to Indonesia is probably intentional. Sites for sharing and showing off music and images, most focusing on self-created content. Straits of Web 2.0 : A strait is a narrow passage between two outcroppings. Web 2.0 is a term used to describe new internet architectures, which these programs and Wikipedia (the other side of the strait) are examples of. Gays of Web 2.0 is a pun: The opposite of a gay person (homosexual) is a straight person (heterosexual). Sites such as Wikipedia and chat programs such as IRC. Need descriptions Sites related to smaller internet communities, a.k.a. "Subcultures." Also, a whole lot of internet memes, unsurprisingly. The "Viral Straits" references the idea of something "going viral," i.e. spreading quickly to huge numbers of people on the internet. These sites are often responsible for things going viral, and the memes listed are ones that went viral in the past. Sites Memes and related An area dedicated to MMORPGs (Massively Multiplayer Online Roleplaying Games), large-scale games with huge numbers of players put into the same world. The label "Here there be anthromorphic dragons" references a common marking on old maps ("Here there be dragons") but updates it to joke about the more humanoid dragons seen in many games, or again, how dragons, especilally anthropomorphic dragons, are very-very popular in the furry community. [Hand-drawn fantasy style map with land and sea areas representing populations of online communities. Each area or item is labeled.] Map of Online Communities and related points of interest Geographic area represents estimated size of membership [Land Area Labels:] The Icy North (Yahoo, Windows Live), AOL, Chat Rooms Reunion dot com, Classmates dot com, E-harmony, Friendster, Faceparty, Chasm, Qwghlm, Yahoo Games, Mountains of Web 1.0, The Lonely Island, MySpace, Attractive MySpace Pages, The Series of Tubes, Myspace Bands, WOW, Lineage, Second Life, Third Life, UO, EQ, FFXI, 2channel, 4chan, LJ, Xanga, Orkut, Cyworld, Blurty, OK Cupid, Facebook, Piczo, The Compass-Rose-Shaped Island, Practicals (Noob) Focus on Real Life (IRL) Focus on Web (.com) Intellectuals (π) Broadcaster, The Bit Torrent, Flickr, Last.fm, DeviantArt, Isle of Slash, Numa, Digg, Fark, Reddit, Something Awful, Your Base, Soviet Russia, /. [Slashdot], Spaaarta (YTMND), StumbleUpon, Del.icio.us, The Blogipelago, Sulawesi, Xu Jinglei, Post Secret, Technocrati, [Hard to read label: Probably JWB, TWB, or TMZ] BoingBoing, Huffington Post, Gays of Web 2.0, The Wikipedia project, MIT, Engadget, Gizmodo, Usenet, MAKE Blog, IRC Isles, Sourceforge. [Sea Area Labels:] NOOB Sea, Gulf of YouTube, Bay of Angst, Sea of Culture, Ocean of Subculture, P2P Shoals, Straits of Web 2.0, Here Be Anthropomorphic Dragons, Bay of Trolls, Viral Straits, Sea of Memes, The Wet Sea Item Labels: Shipwreck of the SS Howard Dean, Cory Doctrow's Balloon, Stallman's airship, Google's volcano fortress (Not a complete survey. Sizes based on the best figures I could find but involved some guesswork. Do not use for navigation.) Spring 2007

Code Talkers

Code Talkers

https://www.xkcd.com/257

https://www.explainxkcd.com/wiki/index.php/257:_Code_Talkers

[A man is looking at a computer monitor and speaking into a microphone.] Code talker: A'la'ih, do'neh'lini, do'neh'lini, a'la'ih, a'la'ih, do'neh'lini, do'neh'lini, do'neh'lini, a'la'ih, a'la'ih, do'neh'lini, a'la'ih, do'neh'lini,do'neh'lini, do'neh'lini... [Two men are talking nearby.] Cueball: For added security, after we encrypt the data stream, we send it through our Navajo code talker. Friend: ...Is he just using Navajo words for "Zero" and "One"? Cueball: Whoa, hey, keep your voice down!

Code talkers are people who communicate using their native language not known by the enemies. The most well-known code talkers were the Navajo-speaking Marines serving during World War II. This comic shows a Navajo code talker transmitting an encrypted binary file by speaking "one" and "zero" (actually "neutral," as explained in the title text) into a microphone. By using only two words, the code is easily cracked. Unlike the Navajo Marines, this process does not add security, because it easily can be decrypted and is also much slower than simply transmitting the file over a network. Note that (probably unbeknownst to Randall) the actual code used by the Navajo code talkers was not so far removed from the depiction in the comics: The Navajos used a mostly alphabetic code, with one Navajo word for each English letter. (This meant that even though the Axis captured at least one native Navajo speaker, he could not make any sense of what was said.) However, several important terms were given their own Navajo idioms, so the entropy would be somewhat higher than depicted in the comic. The title text is a disclaimer from Randall about using "neutral" instead of "zero" — Navajo has words for the concept of nothing, but not for the numeral zero. Most number systems are not positional , and therefore may lack the number zero. The Arabic numeral system used in the West required the invention of the zero as a placeholder, so that numbers could retain their position when one column has nothing in it. [A man is looking at a computer monitor and speaking into a microphone.] Code talker: A'la'ih, do'neh'lini, do'neh'lini, a'la'ih, a'la'ih, do'neh'lini, do'neh'lini, do'neh'lini, a'la'ih, a'la'ih, do'neh'lini, a'la'ih, do'neh'lini,do'neh'lini, do'neh'lini... [Two men are talking nearby.] Cueball: For added security, after we encrypt the data stream, we send it through our Navajo code talker. Friend: ...Is he just using Navajo words for "Zero" and "One"? Cueball: Whoa, hey, keep your voice down!

Conspiracy Theories

Conspiracy Theories

https://www.xkcd.com/258

https://www.explainxkcd.com/wiki/index.php/258:_Conspiracy_Theories

Hairy: The official story of 9-11 is full of holes. Take the— Cueball: Please, stop, because seeing this happen to you breaks my heart. Cueball: Conspiracy theories represent a known glitch in human reasoning. The theories are of course occasionally true, but their truth is completely uncorrelated with the believer's certainty. For some reason, sometimes when people think they've uncovered a lie, they raise confirmation bias to an art form. They cut context away from facts and arguments and assemble them into reassuring litanies. And over and over I've argued helplessly with smart people consumed by theories they were sure were irrefutable, theories that in the end proved complete fictions. Cueball: Young-Earth Creationists, the Moon Landing people, the Perpetual Motion subculture — can't you see you're falling into the same pattern? Hairy: You don't seriously believe we landed on the moon, do you? [Cueball walks away, frustrated.] [Cueball kneels down with folded hands, praying:] Cueball: Dear God. [Booming from the sky:] God: YES, MY CHILD? Cueball: I would like to file a bug report.

A conspiracy theory purports to explain a social, political, or economic event as being caused or covered up by a covert group or organization. A typical example is the moon landing conspiracy , which asserts that no human has ever reached the moon. Once a conspiracy theory starts, it often grows stronger. Facts agreeing with the theory are, of course, evidence for the theory. Facts disagreeing with the theory are considered part of the cover-up and thus prove there is, in fact, a cover-up, so they're also evidence for the theory. In the Moon landing case, videos of men walking on the Moon are assumed to be faked by Hollywood studios, so the existence of the assumed fake videos proves the cover-up. Also, the absence of filming crew or anything else needed for faking a video is considered further proof of how carefully the cover-up was planned. No matter what happens next, it will be evidence for the conspiracy theory. As one person put it: "To a conspiracy theorist, there are only two kinds of evidence: evidence that proves their theory correct, and evidence that proves the conspiracy goes deeper than they ever imagined ." People promoting these theories belong to a small minority, but they gain attention from many people — often without much knowledge on that specific matter. People who have actual knowledge about a given subject just get frustrated by this, because it seems like smart or educated people should reject conspiracy theories for lack of proof (if a conspiracy theory has proof, it's really science or investigative journalism). In the comic, Hairy (who is considered "smart" by Cueball ) starts pointing out "errors" in the "official" 9/11 story , obviously starting to describe the 9/11 conspiracy theory . Cueball cuts his speech sharply, and his heart is broken because he's seeing his smart friend wasting his great intelligence in a foolish conspiracy theory, instead of doing something useful. In the second panel, Cueball rants about conspiracy theories in general. He mentions Young Earth creationism , the Moon landing , and Perpetual motion machines. In the third panel, Hairy mentions that of course we never landed on the moon. This frustrates Cueball so much that he just walks away with no further comment. In the last panel, Cueball asks God to fix the bug he committed when creating smart beings capable of believing such foolish things as conspiracy theories. This is a not-so-subtle joke as, to atheists, God himself is quite similar to a conspiracy theory. Indeed, a good portion of evidence against God's existence put forward by an atheist is met with a "whatever happens, it's God's will" by a believer. This is much like any other conspiracy theory, so in this last panel, to a subset of atheists, Cueball is pictured as contradicting himself by complaining that other people believe in foolish conspiracy theories while the atheist may think that Cueball himself is very plainly believing his own foolish conspiracy theory. Of course, from the believers' perspective, some such schools of atheistic thought also have many characteristics of a conspiracy theory. In particular, atheism and agnosticism are a small subculture — actually smaller in the U.S. than the 9/11 Truth movement — of which many believe that a large majority of people (about 95% of Americans believe in God ) have been deluded into believing something ridiculous by conspiracies (e.g. churches and conservative politicians) that benefit from the spreading of misinformation on the subject. A "bug report" is a description of some error that occurred when using a computer program, to inform the developer of a problem that needs to be fixed. Filing a "bug report" to God should be unnecessary, as God is generally understood by believers to be omniscient, and thus already aware of the problem. God allows it to exist for explicable reasons of "God's will." The title text refers the large number of educated people who believe in Young Earth creationism , stating that the earth is only thousands of years old, instead of the billions of years evolutionary scientists suggest. Hairy: The official story of 9-11 is full of holes. Take the— Cueball: Please, stop, because seeing this happen to you breaks my heart. Cueball: Conspiracy theories represent a known glitch in human reasoning. The theories are of course occasionally true, but their truth is completely uncorrelated with the believer's certainty. For some reason, sometimes when people think they've uncovered a lie, they raise confirmation bias to an art form. They cut context away from facts and arguments and assemble them into reassuring litanies. And over and over I've argued helplessly with smart people consumed by theories they were sure were irrefutable, theories that in the end proved complete fictions. Cueball: Young-Earth Creationists, the Moon Landing people, the Perpetual Motion subculture — can't you see you're falling into the same pattern? Hairy: You don't seriously believe we landed on the moon, do you? [Cueball walks away, frustrated.] [Cueball kneels down with folded hands, praying:] Cueball: Dear God. [Booming from the sky:] God: YES, MY CHILD? Cueball: I would like to file a bug report.

Clichéd Exchanges

Clich&eacute;d Exchanges

https://www.xkcd.com/259

https://www.explainxkcd.com/wiki/index.php/259:_Clich%C3%A9d_Exchanges

My Hobby: Derailing clichéd exchanges by using the wrong replies Friend: O RLY? Cueball: O RLY? I 'ardly know 'er!

Another entry into the My Hobby series. " O RLY? " is an Internet meme typically used to express sarcastic agreement with or feigned surprise at a statement. The typical response to "O RLY" is usually "YA RLY," "NO WAI," or "SRSLY?" These exchanges are memetic variatons of "Oh really?", "Yeah really," "No way!", and "Seriously?" respectively. However, Cueball 's response avoids this typical exchange, instead replying with another cliché, derived from a classic double entendre. In this cliché, the speaker responds to a statement containing a word ending with '-er' and turns it into a sexual reference. The setup is as follows: Alice: "Do you want to come over to my house? My wife and I are playing poker." Bob: "Poker? I hardly KNOW her!" Such a double entendre makes no sense in the context of an O RLY exchange. In the case of the comic, the non-sequitur will likely baffle the person setting up the meme and derail the conversation, to the amusement of the replying person. The reason Randall makes this a hobby is, presumably, that it bores him when people fall back on clichés for comedy, and he seeks inventive ways to humor himself in these situations. This view has already been expressed early in 16: Monty Python -- Enough The title text takes the real cliché "fight fire with fire" and combines it with the more literal "fight clichés with clichés." The resulting statement follows a very similar principle to the situation in the comic proper. My Hobby: Derailing clichéd exchanges by using the wrong replies Friend: O RLY? Cueball: O RLY? I 'ardly know 'er!

The Glass Necklace

The Glass Necklace

https://www.xkcd.com/260

https://www.explainxkcd.com/wiki/index.php/260:_The_Glass_Necklace

[There is only one large panel in this comic, but it is still divided up into 19 individual scenes, one following the other, but of very different size and details. In every scene, there is at least one word noted, mainly just stating what Cueball does. The first row has four scenes (1-4), the second row only two (5-6), the third row has three (7-9), the fourth four (10-13), the fifth five (14-18), and then the last scene takes up the middle of the sixth row (19).] [Scene 1: Cueball is seen sitting behind a table facing out of the panel drawing on a paper with a cup next to him on the table. An arrow points down to the paper from above where the sketch he is drawing is shown on a zoom in on the paper. He has drawn a cylinder shown in the top left, next to it is a detailed diagram of the cylinder in a cross section down its length, showing that it is hollow, with electrical terminals on either end. The dimensions of the cylinders length, both inner and outer, are indicated on each side of this diagram. Below right is a cross section through circular section indicating the diameter. At the bottom left, there is an instruction showing that the cylinder can be opened in one end, and and an arrow with a label points into the open cylinder. The label can be read, but the dimensions are unreadable.] Draw Label: Sand [Scene 2: Cueball is at a workbench making the device in a workshop. The main part of the cylinder can already be seen lying on the table, as Cueball works on another part. His sketch is also resting on the table leaning up against the rear part of the workbench where four rows with three small drawers in each row are closed, except the second row from the top, where there are only two drawers, the left of those two drawers standing open. On the edge of the table, two tools looking like hammers hang down. On the floor lie three small rectangular items.] Make Make [Scene 3: Cueball kneels down on a beach and scoops up sand in a beaker. To the left, a fairly large wave (the surf) can be seen far down along the beach. Above the sea, there are a large cloud and a smaller one. To the right of the beach is a dense forest growing close to the surf. The tree trunks are visible, as are the leaves, but most trees and trunks are not possible to single out, except one large tree standing a little further out than the rest just behind Cueball. The trunk of this tree looks a little like a palm tree trunk, but it has a regular crown of normal leaves.] Scoop [Scene 4: Cueball, sitting behind a table, pours the sand from the beaker into the cylinder. The lid of the cylinder lies on the table next to a full glass. It is not clear if it is full of water or just more sand. The beaker used to pour sand is not transparent like the glass on the table is.] Pour [Scene 5: Cueball ties a spool of string to one end of the cylinder and ties a deflated weather balloon, lying on the ground to the right, to the other end. The spool lies on the ground to the left.] Tie [Scene 6: The weather balloon is inflated, and Cueball raises it up into the clouds as thunder rumbles in the huge dark clouds to the right. The cylinder is clearly visible just below the balloon. To the left towards the horizon, there is something that may be a distant city, but there are some lines going away from it away from the horizon, the meaning of which is unclear, could be electrical wires in the air for transporting electricity.] Rumble [Scene 7: Cueball has left after having tied the end of the string to a stake in the ground. The sky is completely covered with clouds, and the first lightning is flashing in the background, thunder following. The balloon hangs close to the clouds, the cylinder barely visible at this distance.] Boom [Scene 8: Lightning hits the balloon and travels all the way down to the rod, which can just be seen at the bottom. There is a loud crack, and the incandescent balloon inside the lightning hisses.] Crack TSSS [Scene 9: A slim image with a zoom-in just of the cylinder as the lightning hits, showing it attached to the wires going up and down from each of the two terminals. The lightning travels along the wire through the cylinder and out the other wire, fusing the sand contents within.] Fuse [Scene 10: The clouds are disappearing to the left, and the sun is out again to the left. Two birds fly in the distance near the sun, and below them there is a hill in the horizon. Cueball, holding onto the string with one hand, follows the string to the cylinder lying on the ground. Above this scene, there is a frame with a caption:] Later Follow [Scene 11: Cueball detaches the cylinder from the wire that goes to the remains of the burned out balloon lying on the ground to the right. The other part of the wire still hangs down from the cylinder's other end.] Detach [Scene 12: Zoom in on Cueball as he opens the cylinder, letting a wisp of smoke out. The cylinder has clearly been exposed to some rough condition, its surface flaking off. Cueball's hands are clearly visible, which is an unusual style in xkcd.] Open [Scene 13: Cueball puts his hands into the cylinder and removes a piece of glass with a zigzag shape. Leftover sand pouts out as he draws it out of the open cylinder.] Remove [Scene 14: Back at his table (with only the surface shown), Cueball admires the piece of glass, holding it between both of his hands. The broken and open cylinder lies on the table, sand pouring out, while the lid lies to the left.] Admire [Scene 15: Cueball is looking at White Hat (a jeweler) standing behind his desk under a large sign hanging from a string put over a peck in the wall above the desk. White Hat examines the glass, holding it up in his hand and looking at it with a magnifying glass he is holding up to his eye. A lamp is standing on the table.] Sign: Jeweler Examine [Scene 16: White Hat, only, grinds the glass on a grindstone he has put on his desk, pieces of glass seeming to fly away from the stone. There are four indeterminate tools lying on the table.] Grind [Scene 17: White Hat, only, sets the now-shining glass in a necklace, having cleared the table from any other items.] Set [Scene 18: Cueball holds the glass necklace in both hands, looks at it, and approves the final result, while White Hat stands behind his desk with something small and rectangular in his hand, probably the money Cueball paid for his service.] Approve [Scene 19: Cueball gives the glass necklace to Megan, almost touching it and her hands with an outstretched hand. Megan admires the shining piece of glass she now holds in her hands, the string hanging down from her hands.] Give

This is one of the most romantic comics published in xkcd. The heat from a lightning strike can fuse sand into glass . When this occurs in nature, hollow tubes called fulgurites are formed. Cueball uses this knowledge and a spark of handiness and ingenuity to create an entirely homemade glass necklace for Megan . Here is some inspiration to do it yourself. The title text represents an answer to the logical question prompted by this comic, which is "Would this actually work?" The implied answer is "Yes," but only "for some value of 'actually work'." This is a play on the phrase "for some value of x," used frequently in physics or mathematics when it's not necessary (nor easy, maybe not even possible) to calculate a suitable value of x. For example, if you supply energy to a Flux Capacitor , could it turn a DeLorean into a time machine? The answer is yes, if you have sufficient energy (the 'some value of x' in this case). Most people would take the title text to mean that the process most likely "doesn't actually work." But a romantic person (who may be in love and thus not as sensible) might give it a try anyway. Well, at least it worked for Cueball.... [There is only one large panel in this comic, but it is still divided up into 19 individual scenes, one following the other, but of very different size and details. In every scene, there is at least one word noted, mainly just stating what Cueball does. The first row has four scenes (1-4), the second row only two (5-6), the third row has three (7-9), the fourth four (10-13), the fifth five (14-18), and then the last scene takes up the middle of the sixth row (19).] [Scene 1: Cueball is seen sitting behind a table facing out of the panel drawing on a paper with a cup next to him on the table. An arrow points down to the paper from above where the sketch he is drawing is shown on a zoom in on the paper. He has drawn a cylinder shown in the top left, next to it is a detailed diagram of the cylinder in a cross section down its length, showing that it is hollow, with electrical terminals on either end. The dimensions of the cylinders length, both inner and outer, are indicated on each side of this diagram. Below right is a cross section through circular section indicating the diameter. At the bottom left, there is an instruction showing that the cylinder can be opened in one end, and and an arrow with a label points into the open cylinder. The label can be read, but the dimensions are unreadable.] Draw Label: Sand [Scene 2: Cueball is at a workbench making the device in a workshop. The main part of the cylinder can already be seen lying on the table, as Cueball works on another part. His sketch is also resting on the table leaning up against the rear part of the workbench where four rows with three small drawers in each row are closed, except the second row from the top, where there are only two drawers, the left of those two drawers standing open. On the edge of the table, two tools looking like hammers hang down. On the floor lie three small rectangular items.] Make Make [Scene 3: Cueball kneels down on a beach and scoops up sand in a beaker. To the left, a fairly large wave (the surf) can be seen far down along the beach. Above the sea, there are a large cloud and a smaller one. To the right of the beach is a dense forest growing close to the surf. The tree trunks are visible, as are the leaves, but most trees and trunks are not possible to single out, except one large tree standing a little further out than the rest just behind Cueball. The trunk of this tree looks a little like a palm tree trunk, but it has a regular crown of normal leaves.] Scoop [Scene 4: Cueball, sitting behind a table, pours the sand from the beaker into the cylinder. The lid of the cylinder lies on the table next to a full glass. It is not clear if it is full of water or just more sand. The beaker used to pour sand is not transparent like the glass on the table is.] Pour [Scene 5: Cueball ties a spool of string to one end of the cylinder and ties a deflated weather balloon, lying on the ground to the right, to the other end. The spool lies on the ground to the left.] Tie [Scene 6: The weather balloon is inflated, and Cueball raises it up into the clouds as thunder rumbles in the huge dark clouds to the right. The cylinder is clearly visible just below the balloon. To the left towards the horizon, there is something that may be a distant city, but there are some lines going away from it away from the horizon, the meaning of which is unclear, could be electrical wires in the air for transporting electricity.] Rumble [Scene 7: Cueball has left after having tied the end of the string to a stake in the ground. The sky is completely covered with clouds, and the first lightning is flashing in the background, thunder following. The balloon hangs close to the clouds, the cylinder barely visible at this distance.] Boom [Scene 8: Lightning hits the balloon and travels all the way down to the rod, which can just be seen at the bottom. There is a loud crack, and the incandescent balloon inside the lightning hisses.] Crack TSSS [Scene 9: A slim image with a zoom-in just of the cylinder as the lightning hits, showing it attached to the wires going up and down from each of the two terminals. The lightning travels along the wire through the cylinder and out the other wire, fusing the sand contents within.] Fuse [Scene 10: The clouds are disappearing to the left, and the sun is out again to the left. Two birds fly in the distance near the sun, and below them there is a hill in the horizon. Cueball, holding onto the string with one hand, follows the string to the cylinder lying on the ground. Above this scene, there is a frame with a caption:] Later Follow [Scene 11: Cueball detaches the cylinder from the wire that goes to the remains of the burned out balloon lying on the ground to the right. The other part of the wire still hangs down from the cylinder's other end.] Detach [Scene 12: Zoom in on Cueball as he opens the cylinder, letting a wisp of smoke out. The cylinder has clearly been exposed to some rough condition, its surface flaking off. Cueball's hands are clearly visible, which is an unusual style in xkcd.] Open [Scene 13: Cueball puts his hands into the cylinder and removes a piece of glass with a zigzag shape. Leftover sand pouts out as he draws it out of the open cylinder.] Remove [Scene 14: Back at his table (with only the surface shown), Cueball admires the piece of glass, holding it between both of his hands. The broken and open cylinder lies on the table, sand pouring out, while the lid lies to the left.] Admire [Scene 15: Cueball is looking at White Hat (a jeweler) standing behind his desk under a large sign hanging from a string put over a peck in the wall above the desk. White Hat examines the glass, holding it up in his hand and looking at it with a magnifying glass he is holding up to his eye. A lamp is standing on the table.] Sign: Jeweler Examine [Scene 16: White Hat, only, grinds the glass on a grindstone he has put on his desk, pieces of glass seeming to fly away from the stone. There are four indeterminate tools lying on the table.] Grind [Scene 17: White Hat, only, sets the now-shining glass in a necklace, having cleared the table from any other items.] Set [Scene 18: Cueball holds the glass necklace in both hands, looks at it, and approves the final result, while White Hat stands behind his desk with something small and rectangular in his hand, probably the money Cueball paid for his service.] Approve [Scene 19: Cueball gives the glass necklace to Megan, almost touching it and her hands with an outstretched hand. Megan admires the shining piece of glass she now holds in her hands, the string hanging down from her hands.] Give

Regarding Mussolini

Regarding Mussolini

https://www.xkcd.com/261

https://www.explainxkcd.com/wiki/index.php/261:_Regarding_Mussolini

[Three people are standing around a map. One of them is pushing something with a stick.] [A messenger arrives.] Messenger: General, Italian forces have entered Egypt. General: As I expected. This is a foolish move by Mussolini, but like Hitler he will no doubt force his commanders to— Messenger: Hey. Godwin's Law. General: Dammit. General: You know, this may become a problem.

Godwin's Law states that all debates on the Internet, given enough time, will devolve into ad hominem attacks in the form of comparisons of one's opponents to Hitler or the Nazis. A common expansion on this law dictates that, when such a comparison is brought up, the debate immediately ends and the person who made the reference is declared the loser. This is meant to dissuade ad hominem (or in this case " Ad hitlerum ") attacks on other people/subjects, where their views are unreasonably compared to those held by the Nazis, and should not apply to relevant discussions regarding Nazis. The scene in the comic shows generals of the British and Commonwealth forces discussing Benito Mussolini 's invasion of Egypt. Mussolini and Hitler were each commanders of Axis powers during World War II , so comparisons between them are almost certain to arise. The joke is that in this situation, because the conversation is taking place in World War II, Hitler is relevant to the discussion, and, therefore, comparisons made to Hitler are actually valid and not an ad hominem attack. This means that in this case, Godwin's Law should not apply. As the title text suggests, it would have been detrimental to the war effort if the expanded version of Godwin's Law had been enforced by actually ending meetings to plan war strategy whenever Hitler was appropriately mentioned. [Three people are standing around a map. One of them is pushing something with a stick.] [A messenger arrives.] Messenger: General, Italian forces have entered Egypt. General: As I expected. This is a foolish move by Mussolini, but like Hitler he will no doubt force his commanders to— Messenger: Hey. Godwin's Law. General: Dammit. General: You know, this may become a problem.

IN UR REALITY

IN UR REALITY

https://www.xkcd.com/262

https://www.explainxkcd.com/wiki/index.php/262:_IN_UR_REALITY

[Black Hat is holding a cat and a piece of paper. Cueball has raised his arms. There are three cats with captions stuck to them.] Black Hat: Oh hi; I'm here from the Internet. Cueball: What are you doing!? Black Hat: Gluing captions to your cats. Cat: RRRR

The LOLcat meme genre involves pictures of cats in various poses and facial contortions accompanied by deliberately misspelled captions. Black Hat claims to be from the Internet and is thus creating LOLcat memes by literally gluing captions to Cueball's cats. The title text suggests that Black Hat is using glue only because he ran out of staples; fortunately for the cats in the picture, glue is much less painful than a staple. The title text suggests that Black Hat was stapling captions to cats earlier. This either means that Black Hat has injured some of Cueball's cats, just not the ones on screen (which would imply that Cueball has very many cats, since Black Hat would have brought a fair number of staples to begin with) or that Black Hat injured other people's cats before going to Cueball's house in order to caption the cats there. The title is also a reference to the "I'm in ur base killing ur d00dz" catchphrase from real-time-strategy games. Stapling things to other things has also been referenced in 291: Dignified and 478: The Staple Madness . Being "from the Internet" was spoken of in the title text of 256: Online Communities . [Black Hat is holding a cat and a piece of paper. Cueball has raised his arms. There are three cats with captions stuck to them.] Black Hat: Oh hi; I'm here from the Internet. Cueball: What are you doing!? Black Hat: Gluing captions to your cats. Cat: RRRR

Certainty

Certainty

https://www.xkcd.com/263

https://www.explainxkcd.com/wiki/index.php/263:_Certainty

[A door seen from a hallway, with "Teachers' Lounge" on the glass, next to the door is a sign reading "Award." Inside the door are two teachers talking.] Megan: My students drew me into another political argument. Cueball: Eh; it happens. Megan: Lately, political debates bother me. They just show how good smart people are at rationalizing. [The two teachers continue talking. A third one is seen reading a book on a sofa.] Megan: The world is so complicated - the more I learn, the less clear anything gets. There are too many ideas and arguments to pick and choose from. How can I trust myself to know the truth about anything? And if everything I know is so shaky, what on Earth am I doing teaching? Cueball: I guess you just do your best. No one can impart perfect universal truths to their students. Miss Lenhart: *ahem* Cueball: ...Except math teachers. Miss Lenhart: Thank you.

Megan and Cueball are teachers in this comic, talking about their students and the political discussions with them. They outline that it's not possible to find the real truth. But then Cueball, interrupted by a harrumph of the mathematics teacher Miss Lenhart , states that Mathematics is an exception (because math can actually be proved , conclusively). Randall likes mathematics because mathematical political discussions are not possible. The title text shows a simple valid mathematical equation, the distributive property , and Randall is daring one to politicize it. Though this happened years after the comic was published, people have in fact politicized the distributive property , claiming that teaching it promoted socialism. [A door seen from a hallway, with "Teachers' Lounge" on the glass, next to the door is a sign reading "Award." Inside the door are two teachers talking.] Megan: My students drew me into another political argument. Cueball: Eh; it happens. Megan: Lately, political debates bother me. They just show how good smart people are at rationalizing. [The two teachers continue talking. A third one is seen reading a book on a sofa.] Megan: The world is so complicated - the more I learn, the less clear anything gets. There are too many ideas and arguments to pick and choose from. How can I trust myself to know the truth about anything? And if everything I know is so shaky, what on Earth am I doing teaching? Cueball: I guess you just do your best. No one can impart perfect universal truths to their students. Miss Lenhart: *ahem* Cueball: ...Except math teachers. Miss Lenhart: Thank you.

Choices Part 1

Choices: Part 1

https://www.xkcd.com/264

https://www.explainxkcd.com/wiki/index.php/264:_Choices:_Part_1

[Megan sits at a desk, using a computer, refreshing the page.] *Refresh* Click [She sits back and looks at the monitor.] [She refreshes the page on the computer.] *Refresh* Click [She sits back and looks at the monitor.] [Megan leans forward and clicks the mouse.] Click [A hole opens up in the panel. It appears to be the torn paper of the comic itself. A light-blue, sky-like background is revealed. Megan jumps in surprise, nearly tipping over her chair.] [Megan stands up as the chair falls over completely.] [Wide view. Megan looks back at the door furtively.] [She begins to climb into the hole.] [By now, Megan is entirely inside the hole. She is closing it behind her.] [Only her head and arms are visible.] [The hole is closed, revealing a formation of ripped paper.] [Large frame, where Megan appears to be in space, with blue not black background. Stars dot the sky, and rays of light seem to originate from a point to the right, and then traverse the frame both horizontally and vertically, almost like lightning. Megan is in a bubble, floating disconnectedly. Both she and the bubble have become white, tinged against the backdrop.]

Megan is sitting at her computer, not waiting for a particular mail, but still refreshing every few seconds. This is an illustration of boredom and pointlessness in life. But suddenly the wall in front of her is opening. She considers running for the door, but curiosity overtakes her. She enters the hole, closes it behind her, and with that, she enters a different world. The hole appears as if it is a rip in a sheet of paper, implying that since they are drawings (which they are), this would be essentially a hole in space-time from their perspective. Most people would run away from such a thing, but Megan seems to feel that since she is currently bored (shown by the fact that she is constantly refreshing her E-mail), this is a break from her normal life, and she may not fully be realizing/acknowledging the inherent dangers of leaving her realm into an unknown universe. She does worry that she is missing an email, though, much as a person often does resist breaking from routine. This starts out a metaphoric five-part adventure that celebrates, marvels at, and reminds of human freedom. The series was released on 5 consecutive days (Monday-Friday). All parts of " Choices ": [Megan sits at a desk, using a computer, refreshing the page.] *Refresh* Click [She sits back and looks at the monitor.] [She refreshes the page on the computer.] *Refresh* Click [She sits back and looks at the monitor.] [Megan leans forward and clicks the mouse.] Click [A hole opens up in the panel. It appears to be the torn paper of the comic itself. A light-blue, sky-like background is revealed. Megan jumps in surprise, nearly tipping over her chair.] [Megan stands up as the chair falls over completely.] [Wide view. Megan looks back at the door furtively.] [She begins to climb into the hole.] [By now, Megan is entirely inside the hole. She is closing it behind her.] [Only her head and arms are visible.] [The hole is closed, revealing a formation of ripped paper.] [Large frame, where Megan appears to be in space, with blue not black background. Stars dot the sky, and rays of light seem to originate from a point to the right, and then traverse the frame both horizontally and vertically, almost like lightning. Megan is in a bubble, floating disconnectedly. Both she and the bubble have become white, tinged against the backdrop.]

Choices Part 2

Choices: Part 2

https://www.xkcd.com/265

https://www.explainxkcd.com/wiki/index.php/265:_Choices:_Part_2

[Cueball is doing some exercises in a book. The clock on the wall says 12:50.] Chapter 15: Special Relativity Problem 1: Two spacecraft transmit messages to each other while passing at constant velocities of... Cueball: sigh Meanwhile: [Megan in a bubble and a spacecraft are moving towards each other. Each one has a velocity vector drawn before themselves, each showing a velocity of 0.2c.] [They pass each other.] Spacecraft: We observe your speed to be 38.5%c, and your time is passing at 92.3% the rate of ours. Does this mirror your observations? Megan: Please help me. I think I'm lost. [They continue with the same velocity vectors. Megan is looking back at the spacecraft.]

The "Choices" series was released on 5 consecutive days (Monday-Friday). It explores and marvels at human freedom. This is, however, a little sidetrack from the "Choices" narrative. Cueball is studying special relativity . The speed of light in a vacuum (299,792,458 m/s) is denoted as c . Megan and the spaceship are shown traveling at 0.2 c in opposite directions. This would mean (in Newtonian mechanics) 0.4 c relative to each other. But due to relativistic effects, their velocities do not simply add when the spaceship observes Megan; in reality, both would measure only 0.385 c ( = (u + v)/(1 + uv/c 2 ) ) from the other's point of view. Also, time dilation influences the way time is observed with reference to the two frames of reference. Megan, however, has other concerns. (This text and part of the image were completely reused in the space part of the interactive 1350: Lorenz (see image here ). In the title text, Megan thinks about writing about this after-worldly place in Wikipedia, but then realizes that the content would be removed, due to the Wikipedia policy on original research , meaning that you are discouraged from writing your own thoughts, the preference being that you have a source you're paraphrasing. Even though her claims would be true, she would need reliable written sources to support them. The series was released on 5 consecutive days (Monday-Friday). All parts of " Choices ": As this was the second in the series, it was released on a Tuesday. [Cueball is doing some exercises in a book. The clock on the wall says 12:50.] Chapter 15: Special Relativity Problem 1: Two spacecraft transmit messages to each other while passing at constant velocities of... Cueball: sigh Meanwhile: [Megan in a bubble and a spacecraft are moving towards each other. Each one has a velocity vector drawn before themselves, each showing a velocity of 0.2c.] [They pass each other.] Spacecraft: We observe your speed to be 38.5%c, and your time is passing at 92.3% the rate of ours. Does this mirror your observations? Megan: Please help me. I think I'm lost. [They continue with the same velocity vectors. Megan is looking back at the spacecraft.]

Choices Part 3

Choices: Part 3

https://www.xkcd.com/266

https://www.explainxkcd.com/wiki/index.php/266:_Choices:_Part_3

[A white Megan floats in a bubble against a dark blue space backdrop. She is at the top of the bubble. Her thoughts (not connected to her by a speak line) are shown above her in white.] Megan (thinking): I should feel scared. [She falls from the top of the bubble, the bubble rises, or both.] Megan (thinking): But I don't. [She hits the bottom of the bubble, and the bubble begins to fall down.] Megan (thinking): Maybe this is a dream. [She floats over the top of the now still bubble.] Megan (thinking): But it doesn't feel like one. [She now floats in the middle of the still bubble, in a larger panel. The sky behind her now has many stars and light effect. A voice speaks from off-panel above.] Voice (off panel): Okay, found you. Megan: Who are you? Voice (off panel): Er, hang on. Voice (off panel): This next part might be a little weird. [Beat panel, where Megan just floats in her bubble on the same background, but in a smaller panel.] [A large panel where many distorted copies of Megan whirl around the original Megan in her bubble; she also bends backwards. The stars and light display in the background is more clear around her bubble, that now creates a lens effect, that even distorts the distorted Megans even more. Around her bubbles edge and the lens edge, there are three places where brown lines appear on both these edges.] [All the copies have disappeared except for one who is hanging suspended outside Megan in her bubble. The new one is almost a mirror image, but not quite. The background is more dark blue, with fewer features.] [The Megan copy raises her hand and speaks. There are again more stars in the background.] Megan copy: Sorry — hi, me. Megan: ...Hi.

Megan is very unsure about what to think of her situation. Is it a dream? Is she in danger? She should be scared but isn't, and it does not feel like a dream, i.e. it feels real even though she suspects it is a dream. This would usually never be the case. If your dream feels realistic, you do not usually consider that you are dreaming. Suddenly someone talks off-panel and tells Megan that she has been found. When Megan asks the speaker who it is, reality becomes even more distorted, and suddenly she finds that she is looking at herself outside the sphere. And the two Megans say hi.... This could be an allusion to The Matrix. The Megan outside the sphere was looking for and has found the Megan inside the sphere, as in The Matrix, Morpheus has been looking for and has found Neo; then Morpheus/outer Megan pulls their target out of the target's reality and comment similarly on how this experience is likely to feel. Outer Megan, as she manifests before Inner Megan: "This next part might be a little weird"; Morpheus, as he is about to plug in Neo for the first time and explain what the Matrix is: "This will feel a little weird." If true, this would not be the only time Randall used The Matrix in xkcd ( e.g. , 566: Matrix Revisited ). In the title text, she realizes that if she were in real space, she wouldn't be able to hear any sound , like the voice talking to her, due to the lack of atmosphere. As an afterthought, she decides to ask about the hole in reality (which many people would consider to be more unusual than sound in space). The series was released on 5 consecutive days (Monday-Friday). All parts of " Choices ": [A white Megan floats in a bubble against a dark blue space backdrop. She is at the top of the bubble. Her thoughts (not connected to her by a speak line) are shown above her in white.] Megan (thinking): I should feel scared. [She falls from the top of the bubble, the bubble rises, or both.] Megan (thinking): But I don't. [She hits the bottom of the bubble, and the bubble begins to fall down.] Megan (thinking): Maybe this is a dream. [She floats over the top of the now still bubble.] Megan (thinking): But it doesn't feel like one. [She now floats in the middle of the still bubble, in a larger panel. The sky behind her now has many stars and light effect. A voice speaks from off-panel above.] Voice (off panel): Okay, found you. Megan: Who are you? Voice (off panel): Er, hang on. Voice (off panel): This next part might be a little weird. [Beat panel, where Megan just floats in her bubble on the same background, but in a smaller panel.] [A large panel where many distorted copies of Megan whirl around the original Megan in her bubble; she also bends backwards. The stars and light display in the background is more clear around her bubble, that now creates a lens effect, that even distorts the distorted Megans even more. Around her bubbles edge and the lens edge, there are three places where brown lines appear on both these edges.] [All the copies have disappeared except for one who is hanging suspended outside Megan in her bubble. The new one is almost a mirror image, but not quite. The background is more dark blue, with fewer features.] [The Megan copy raises her hand and speaks. There are again more stars in the background.] Megan copy: Sorry — hi, me. Megan: ...Hi.

Choices Part 4

Choices: Part 4

https://www.xkcd.com/267

https://www.explainxkcd.com/wiki/index.php/267:_Choices:_Part_4

[Megan in a bubble is floating in outer space (on a dark blue background) next to her clone outside the bubble. Megan is simulating sitting down in the middle of the bubble. The clone reaches one arm out toward the bubble. There is no line from the first part of the clone's text to the rest of the text. It is given from the context who speaks. There are always more stars in the panels to the left than those to the left.] Clone: I shouldn't do this, but I pulled you out for a moment to give you a hint. Megan: A hint? Clone: Take wrong turns. Talk to strangers. Open unmarked doors. And if you see a group of people in a field, go find out what they're doing. Do things without always knowing how they'll turn out. [Megan leans towards the clone, the clone "lies" on her tummy with arms forward and legs lifted up.] Megan: Why tell me this? Clone: You're curious and smart and bored, and all you see is the choice between working hard and slacking off. There are so many adventures that you miss because you're waiting to think of a plan. To find them, look for tiny interesting choices. And remember that you are al ways making up the future as you go. [Megan is "sitting" down with her hands on her knees. The clone stands and lifts an arm up.] Megan: So, wait, what is this place? Am I going to wake up thinking this was a dream? Clone: This is... Think of this as after the game, outside the theatre. To go in, I had to suspend disbelief, forget the outside. [Megan again leans towards the clone; the clone spreads out her arms.] Megan: So you... Huh. Why give me hints I'm going to forget? Clone: You'll forget this trip but I think the hints should stay with you. Megan: ...If this is a game, are you— are we — cheating? Clone: Yup. [Megan still leans towards the clone. The clone leans a little back, her arms down.] Megan: Is that a good idea? Clone: Well it's an interesting one. We'll see how it goes. Megan: Well, I guess I'll see you aroun— [Megan leans towards the clone with a hand up, the clone leaning even more back, almost like she is falling backwards.] Megan: Wait a minute; have you brought me here before? Clone: I ... Maybe. Once. Megan: For another hint? Clone: Er. Clone: Actually we just made out. Megan: We wh— Clone: Bye!

This is the existentialistic climax of the Choices series. It takes up the recurring xkcd -theme how people tend to be blind towards the staggering amount of possibilities that each day holds, with routine and boredom as a result. (See e.g. 137: Dreams and 706: Freedom .) The Megan -clone implies that Megan has been taken to some kind of afterlife or parallel universe outside reality. It's not a dream, but she will not remember this place when she goes back. But the clone hopes that these hints will stay with her. Realizing that she would not remember being here, Megan suddenly realizes that she might already have been here before. And the clone admits that she has taken her to this place once before. Although not for another hint; actually it was to make out with herself. And then she quickly says bye . The title text makes it clear that the Megan-clone did actually bring her previously into this place just to make out, and then refers to this being the second time this has been a theme, 105: Parallel Universe being the first. Randall appears to find this a little troubling (or it may be that he suspects his readers will). The series was released on 5 consecutive days (Monday-Friday). All parts of " Choices ": As this was the fourth in the series, it was released on a Thursday. [Megan in a bubble is floating in outer space (on a dark blue background) next to her clone outside the bubble. Megan is simulating sitting down in the middle of the bubble. The clone reaches one arm out toward the bubble. There is no line from the first part of the clone's text to the rest of the text. It is given from the context who speaks. There are always more stars in the panels to the left than those to the left.] Clone: I shouldn't do this, but I pulled you out for a moment to give you a hint. Megan: A hint? Clone: Take wrong turns. Talk to strangers. Open unmarked doors. And if you see a group of people in a field, go find out what they're doing. Do things without always knowing how they'll turn out. [Megan leans towards the clone, the clone "lies" on her tummy with arms forward and legs lifted up.] Megan: Why tell me this? Clone: You're curious and smart and bored, and all you see is the choice between working hard and slacking off. There are so many adventures that you miss because you're waiting to think of a plan. To find them, look for tiny interesting choices. And remember that you are al ways making up the future as you go. [Megan is "sitting" down with her hands on her knees. The clone stands and lifts an arm up.] Megan: So, wait, what is this place? Am I going to wake up thinking this was a dream? Clone: This is... Think of this as after the game, outside the theatre. To go in, I had to suspend disbelief, forget the outside. [Megan again leans towards the clone; the clone spreads out her arms.] Megan: So you... Huh. Why give me hints I'm going to forget? Clone: You'll forget this trip but I think the hints should stay with you. Megan: ...If this is a game, are you— are we — cheating? Clone: Yup. [Megan still leans towards the clone. The clone leans a little back, her arms down.] Megan: Is that a good idea? Clone: Well it's an interesting one. We'll see how it goes. Megan: Well, I guess I'll see you aroun— [Megan leans towards the clone with a hand up, the clone leaning even more back, almost like she is falling backwards.] Megan: Wait a minute; have you brought me here before? Clone: I ... Maybe. Once. Megan: For another hint? Clone: Er. Clone: Actually we just made out. Megan: We wh— Clone: Bye!

Choices Part 5

Choices: Part 5

https://www.xkcd.com/268

https://www.explainxkcd.com/wiki/index.php/268:_Choices:_Part_5

[Megan is walking towards the right of the panel.] [Cueball wearing a backpack is walking towards the left of the panel.] [They walk past each other.] [Megan has a sudden thought, in a drawing without a frame between two panels.] [Megan turns, lifts her arm, and calls out to Cueball, who then turn towards her.] Megan: Hi. Cueball: Uh, hi. [Only Megan is shown.] Megan: Sorry if this is weird, but Megan: Do you like flying kites?

In the final part of Choices , Megan is back to real life, and has forgotten about her trip, as afterlife-Megan said. However, she has an epiphany , and in the spirit of what she told her, she talks to the stranger on the street. The stranger is likely Cueball who studied the physics problem she encountered from part 2 , as they both use a similar backpack. The urge to talk to strangers in awkward situations has been touched on in 235: Kite and can also be used when you are already flying a kite (see 1614: Kites .) The title text suggests a weird sociological investigation. The capital "S" in "Science" suggests a personification . The series was released on 5 consecutive days (Monday-Friday). All parts of " Choices ": [Megan is walking towards the right of the panel.] [Cueball wearing a backpack is walking towards the left of the panel.] [They walk past each other.] [Megan has a sudden thought, in a drawing without a frame between two panels.] [Megan turns, lifts her arm, and calls out to Cueball, who then turn towards her.] Megan: Hi. Cueball: Uh, hi. [Only Megan is shown.] Megan: Sorry if this is weird, but Megan: Do you like flying kites?

TCMP

TCMP

https://www.xkcd.com/269

https://www.explainxkcd.com/wiki/index.php/269:_TCMP

[Cueball stand with a keyboard next to a bed. The keyboard is connected with a wire to a computer on a desk to the right. He talks to Megan and a Cueball-like friend.] Cueball: Hey, help me test the Trans-Consciousness Messaging Protocol. Friend: What's that? Cueball: I've been training myself to keep my fingers moving slightly as I fall asleep. So I can type from inside dreams. [Cueball sits with the keyboard on the bed.] Cueball: I'm going to sleep now. My computer will relay my messages to you as I explore the dream world. [Cueball stand with the keyboard in a forest with tall trees. The leaves are not visible; they are above the top of the drawing. At the top, there is a frame with text:] In the dream: Cueball (thinking): So strange to think none of this is real. Cueball (thinking): And yet I have this lifeline to the internet back home. [Cueball places the keyboard on a stone, bends down, and types.] Cueball (thinking): A chance to speak from one reality to another. Cueball (thinking): I feel like Bell & Watson. I get to write the inaugural TCMP message. Cueball (thinking): Let's see... Keyboard: *Type type type* [Megan is at the computer, and the Cueball-like friend behind her looks at his message from the dream. At the top, there is a frame with text:] Outside: Megan: "F1RST P0ST!!"? Friend: Great. He's jumped straight to trans-reality trolling.

Cueball trained himself to type while asleep, so he could communicate from inside his dreams. He calls this Trans-Consciousness Messaging Protocol , or TCMP . He succeeds in using this system to send a message from inside his dream, but his friends, Megan and another Cueball, are disappointed when that first message is a trollish "F1rst p0st!!", in this case, "trans-reality trolling", instead of something constructive. Firstposting, or thread sniping , is the practice of posting short messages to brag to others that you found and saw this content first. This practice was far more common at the time this comic was written, when high-traffic and poorly-moderated social media sites tended to display comments in increasing chronological order by default; as such, the oldest comments would be most prominently displayed at the top, while the newest comments would be buried at the bottom. These days, while low-traffic and closely-monitored forums still use this approach, social media sites instead tend to sort comments by rating, so that the most appreciated comments are given the most prominence and trollish comments like the cliche "F1rst p0st!!" are buried. See also 1019: First Post and 1258: First and regarding trolling 493: Actuarial . "Bell & Watson" refers to Alexander Graham Bell and his assistant Thomas A. Watson . Bell is traditionally credited with inventing the telephone , because he was awarded the patent for it, although that is still controversial . His first phone call was to Watson in another part of their lab. The name "TCMP" is likely to be a portmanteau of TCP ( Transmission Control Protocol ) and ICMP ( Internet Control Message Protocol ), which are actual protocols used in computer networking. The title text explains how this protocol, if real, would be of great value in dream research, since you then would not have to worry about forgetting the dreams after waking up like as in 430: Every Damn Morning . You can relay the dreams as you experience them. A possible downside is that in order for this to work, the dream has to be lucid , where the dreamer is aware that they are dreaming. This type of dream is very fascinating to Randall , as mentioned in the title text of 203: Hallucinations . Because this method could not be used to study regular dreams, some possibilities for studying dreams would be limited. [Cueball stand with a keyboard next to a bed. The keyboard is connected with a wire to a computer on a desk to the right. He talks to Megan and a Cueball-like friend.] Cueball: Hey, help me test the Trans-Consciousness Messaging Protocol. Friend: What's that? Cueball: I've been training myself to keep my fingers moving slightly as I fall asleep. So I can type from inside dreams. [Cueball sits with the keyboard on the bed.] Cueball: I'm going to sleep now. My computer will relay my messages to you as I explore the dream world. [Cueball stand with the keyboard in a forest with tall trees. The leaves are not visible; they are above the top of the drawing. At the top, there is a frame with text:] In the dream: Cueball (thinking): So strange to think none of this is real. Cueball (thinking): And yet I have this lifeline to the internet back home. [Cueball places the keyboard on a stone, bends down, and types.] Cueball (thinking): A chance to speak from one reality to another. Cueball (thinking): I feel like Bell & Watson. I get to write the inaugural TCMP message. Cueball (thinking): Let's see... Keyboard: *Type type type* [Megan is at the computer, and the Cueball-like friend behind her looks at his message from the dream. At the top, there is a frame with text:] Outside: Megan: "F1RST P0ST!!"? Friend: Great. He's jumped straight to trans-reality trolling.

Merlin

Merlin

https://www.xkcd.com/270

https://www.explainxkcd.com/wiki/index.php/270:_Merlin

[Cueball and Megan standing by a train on a platform.] Megan: I'm bad at goodbyes. At some level I never think they're for real. Cueball: They make me think of T. H. White's Merlin. [They are still standing at the edge of the platform, but the train is no longer in the frame.] Megan: Oh? Cueball: He lived backwards, remembering the future and not the past. To him, final goodbyes meant nothing, while first hellos were tearful and bittersweet. [Zooming out, the rail closest to the platform becomes visible.] Megan: Huh - so over the years he'd forget all his friends. Megan: Must've been lonely. Cueball: Yeah. He ended up just sitting around at home watching DVDs all day. The best was the time he rented 'Memento'... [Merlin with pointy hat and long white beard is sitting in a couch with the remote, watching TV which emits light and is clearly hooked up to a device (a DVD player).] Merlin: Well, that was straightforward.

Merlin is a wizard who features prominently in various retelling of the legend of King Arthur. The Once and Future King by author T. H. White is one of the most popular versions of the legend, and in it, Merlin is described as living backwards through time, as Cueball and Megan discuss in this comic (this is also briefly mentioned in the musical Camelot , which is based on this version of the story). In the comic, Cueball is speculating philosophically on how this would have affected Merlin's life as he started life with all his memories, and gradually lost them, comparing this to Megan's own sense of unreality at goodbyes. Many old people do, however, end up alone without friends or family. And they may do nothing but watch TV all day. They might also lose their memory. So in this respect, Merlin's last days may not be so different from many real people's, except of course that Merlin was supposed to live in the late 5th and early 6th centuries with no access to DVDs or even TV. Memento is a movie telling the main parts of its story backwards, while a few black-and-white scenes are straightforward. So when Merlin watches the movie, he sees nearly the whole story in its actual order, and the title text drives home the joke by noting that these few scenes, which make more sense to someone with normal perceptions than the rest of the movie, would make less sense to him. Normal old people would not be able to enjoy Memento like Merlin. Although he would of course always have remembered seeing it when he got old, until the day he saw it and then forgot it afterwards... [Cueball and Megan standing by a train on a platform.] Megan: I'm bad at goodbyes. At some level I never think they're for real. Cueball: They make me think of T. H. White's Merlin. [They are still standing at the edge of the platform, but the train is no longer in the frame.] Megan: Oh? Cueball: He lived backwards, remembering the future and not the past. To him, final goodbyes meant nothing, while first hellos were tearful and bittersweet. [Zooming out, the rail closest to the platform becomes visible.] Megan: Huh - so over the years he'd forget all his friends. Megan: Must've been lonely. Cueball: Yeah. He ended up just sitting around at home watching DVDs all day. The best was the time he rented 'Memento'... [Merlin with pointy hat and long white beard is sitting in a couch with the remote, watching TV which emits light and is clearly hooked up to a device (a DVD player).] Merlin: Well, that was straightforward.

Powers of One

Powers of One

https://www.xkcd.com/271

https://www.explainxkcd.com/wiki/index.php/271:_Powers_of_One

Powers of One A mind-expanding look at our world [A sequence, presumably continuing endlessly in both directions, of identical images of a couple lying on a chequered blanket, with a picnic basket, on grass. Each image has a rule at the bottom giving measurements in meters, with the scale in terms of 1 to a particular power. The powers visible are the -1st (part), 0th-2nd, and 3rd (part).]

This is a parody of the short documentary "Powers of 10," which can be found here . As in the documentary, the comic features a man and a woman having a picnic on a blanket. In the documentary, the apparent distance from the scene, and thus the zoom level, gradually changes by a factor of ten every ten seconds (hence the name "Powers of 10": 1, 10, 100, ...). In the comic, powers of one are used. Since all powers of 1 are 1, the image doesn't change at all, showing a series of identical images. The title text refers to the Zen meditation ( zazen ), in which the meditator is supposed to suspend all judgmental thinking and let thoughts pass by without eliciting them consciously and without getting involved in them. Powers of One A mind-expanding look at our world [A sequence, presumably continuing endlessly in both directions, of identical images of a couple lying on a chequered blanket, with a picnic basket, on grass. Each image has a rule at the bottom giving measurements in meters, with the scale in terms of 1 to a particular power. The powers visible are the -1st (part), 0th-2nd, and 3rd (part).]

Linux User at Best Buy

Linux User at Best Buy

https://www.xkcd.com/272

https://www.explainxkcd.com/wiki/index.php/272:_Linux_User_at_Best_Buy

Salesman: Interested in updating your antivirus software? Cueball: Oh, I wouldn't need any of that. [In a spiky speech bubble.] Cueball: I run Linux. [Cueball does a backflip onto a motorcycle.] Flip [Cueball performs a wheelie on the motorcycle.] [Cueball does a hard, donut turn on the motorcycle, kicking up dirt into the salesman's face.] [Cueball speeds off on the motorcycle, leaving the salesman in a cloud of black exhaust.]

Best Buy is an American chain of electronics and media stores. As with many such big box shops, they only sell pre-bundled software and boxed pre-built hardware, where the computers on offer are either Macs or other PCs , usually pre-installed with some variant of the Mac OS X or Windows NT operating system families. Most personal computer hackers/enthusiasts (as opposed merely to workaday computer users) wouldn't be caught dead buying a pre-made computer, preferring instead to build their own using self-selected hardware components and install and configure their own preferred operating systems and software. As such, the subtext is that somebody buying a complete pre-packaged home computer system at Best Buy wouldn't know or care much about computers. The salesperson is trying to sell antivirus software to Cueball because selling such software (e.g. Norton or Kaspersky ) to prospective Windows PC owners is generally a good sales tactic. The vast majority of all computer malware is engineered specifically to exploit Windows, and Windows' inherent anti-malware protection might most charitably be described with the phrase "lacklustre, but not as bad as before." Windows users therefore will want antivirus protection, especially for use on a brand new machine that will soon be connected up to the Internet. Moreover, because the ecosystem of viruses and malware that thrive by infecting Windows PCs is constantly evolving (see 350: Network ) and being redesigned to take advantage of new exploits and fool last-month's antivirus software, it is quite prudent for a Windows PC owner to always keep their malware protection absolutely up-to-date, and many such security suites need to be regularly renewed with new versions. While some viruses and malware can afflict Linux , in general Unix-like operating systems (including Linux distributions and BSD ) are far more robust and secure than Windows, with fewer exploitable vulnerabilities. Perhaps even more importantly, Linux (not counting Android, which was not yet released) has a far smaller consumer market share, therefore offers less incentive to malware makers to target it. Therefore, Cueball is confident (rightfully so) that he will be fine without additional security. Moreover, Linux is free software , which means that anyone is able to audit the code and fix security bugs. Although malware protection usually isn't necessary, if extra protection is desired by the user, such as for tasks requiring very high security standards (such as on servers and supercomputers), there are anti-malware solutions available such as ClamAV . Back in 2007, when the less popular Windows Vista was released and with a stagnant Mac market, many in the Linux community believed that Linux would soon wipe out Windows as the operating system of choice for desktop PCs, after years of slow-but-steady growth. This explains the cheeky triumphalism of the final panels of the comic, in which Cueball hops on his quick, slick vehicle and speeds away. It's worth noting that this desktop reversal has not happened, though Linux did achieve a peak in popularity in 2011 , just as Windows users were laboriously switching from Windows XP to Windows 7 , with Linux peaking again in 2014 and Windows arguably in decline, and in any case, desktop PCs themselves have slowed in sales, losing ground first to laptops and most recently to embedded devices , where Linux use does indeed heavily exceed the competition, e.g. Android (which is loosely based on the Linux kernel) handily out-competing both the previously dominant iPhone (which was first released mere days after this comic) and the never-popular Windows Phone . The title text makes sense in light of the fact that, like Linux, the software design of OS X (both are based on Unix, OS X through Darwin - see 676: Abstraction ) limits the amount of harm that can be done by malicious software, and Macs thus also have fewer viruses and malware than Windows. Apparently, Mac and Linux users flock together just waiting for some salesperson to come along and mistake them for someone gullible enough to use Windows. There is a notion that Macs can't get infected , but Mac malware is on the rise. This is taking the piss out of the smugness sometimes to be found among Mac and Linux users, who may view their preferred systems as hip and different from the "mainstream" Microsoft systems that they feel are manifestly inferior. Salesman: Interested in updating your antivirus software? Cueball: Oh, I wouldn't need any of that. [In a spiky speech bubble.] Cueball: I run Linux. [Cueball does a backflip onto a motorcycle.] Flip [Cueball performs a wheelie on the motorcycle.] [Cueball does a hard, donut turn on the motorcycle, kicking up dirt into the salesman's face.] [Cueball speeds off on the motorcycle, leaving the salesman in a cloud of black exhaust.]

Electromagnetic Spectrum

Electromagnetic Spectrum

https://www.xkcd.com/273

https://www.explainxkcd.com/wiki/index.php/273:_Electromagnetic_Spectrum

[Everything is one big panel.] The Electromagnetic Spectrum These waves travel through the electromagnetic field. They were formerly carried by the aether, which was decommissioned in 1897 due to budget cuts. Other waves: Slinky waves [Cueball and Megan hold the ends of a tangled slinky.] Sound waves [There is a snippet of a frequency band. Between 20 Hz and 20 KHz is labeled "Audible Sound." Towards the top is a line labeled "That high-pitched noise in empty rooms."] The wave [A row of people does a wave.] [Three parallel scales are across the bottom. The first is lambda (m), ranging from 100Mm to 100fm; second is f (Hz), which starts at 1 Hz and reaches 100 THz about 2/3 of the way along, after which the labels read "other entertaining greek prefixes like peta- exa- and zappa-;" last is Q (Gal^2/Coloumb), whose labels are 17, 117, pi, 17, 42, phi, e^pi-pi, -2, 540^50, and 11^2. Above the scales and lined up accurately with the first two are the following:] Power & Telephone (100Mm to 1km) Radio & TV (1km to somewhere between 1m and 10cm); above that are many boxes showing subranges (AM, VHF, UHF, 24/7 NPR pledge drives, a very thin band for the space rays controlling Steve Ballmer, 99.3 "The Fox," 101.5 "The Badger," 106.3 "The Frightened Squirrel," cell phone cancer rays, CIA, ham radio, kosher radio, shouting car dealership commercials.) Microwaves (a bit more than 10cm to a bit more than 1mm); it also has subranges (aliens, just below SETI, wifi, FHF, brain waves, sulawesi, gravity) Toasters (about 1mm to about 100 micrometers) IR (about 100 micrometers to somewhere between 1 micrometer and 1 nm); above that is a bell graph labeled "Superman"s heat vision," with a motorcycle driving up the left side labeled "Jack Black's Heat Vision." Visible light (and, under it, visible dark); above that is a bell graph labeled "sunlight." There's a breakout chart above it showing the visible spectrum from 700nm (red) to 450nm (violet). There's an arrow pointing to where octarine would be, somewhere off to the side. Above that are bars showing the absorption spectra for hydrogen, helium, Depends(R) (yellow only), and Tampax(R) (red only). UV (about 100nm to about 10nm) Miller Light (a thin bar around 10nm) An unlabeled section with a thin line above it showing the frequency of the main death star laser A blocked-off portion labeled "Censored Under Patriot Act." X-rays (from about 1nm to about 10pm); a line above shows the frequency of mail-order x-ray glasses. Somewhere vaguely above the 10pm mark is a potato. Gamma/cosmic rays (10pm and smaller); above that is a bar marked Sinister Google Projects that also trails off into higher frequencies, and blogorays, which are slightly lower.

This panel is a play on the Electromagnetic spectrum , showing a large piece of the spectrum and examples of phenomena that absorb or emit light along the spectra. Such spectra are commonly used in physics or astronomy education contexts when discussing the nature of light. This comic extends it to absurd lengths by including examples that may be variously hyper-specific, humorous, or non-EM phenomena. The first two scales at the bottom show the wavelength λ (in meters) and the frequency f (in Hertz) of the wave. The values are related as λ=c/f, where c is the speed of light. The last line showing Q(Gal²/Coloumb) is nonsense; Gal ( Gallon ) is a unit of liquid volume measurement, and Coloumb is a likely typo for Coulomb , the SI unit of electric charge. Photons do not have volume in the traditional sense of the word, and are electrically neutral (thus carrying no charge). In 1887, the Michelson–Morley experiment proved for the first time that the aether theory was wrong. The year (1897) cited underneath the comic title may be an incorrectly-dated reference to this experiment. Nevertheless, after that time, many physicists like Hendrik Lorentz or Joseph Larmor were still working on some aether theories. Albert Einstein 's theory of Special Relativity in 1905 helped explain the theoretical basis for the lack of aether and was a definitive step in discarding previous work. The wavelength starts at high values on the left and decreases in a logarithmic scale to the right. As a result of the inverse relationship between frequency and wavelength, the frequency scale starts at low values and increases logarithmically. The nonsense Q parameter does not change monotonically with either frequency or wavelength. Both scales are labeled with powers of ten and with metric prefixes . For frequencies above 100 tera- Hertz, it just says "other entertaining Greek prefixes like peta- and exa- and zappa-." The last prefix should be zetta- (denoting a factor of 10 21 ), but is intentionally mislabeled, referencing musician Frank Zappa . Other waves Three drawings of other types of waves than the electromagnetic type: Power and Telephone Radio and TV Microwaves Toasters IR (infrared) Visible light UV (ultraviolet) Miller Light Empty section Censored under Patriot Act X-rays Gamma/Cosmic rays And finally, the Title Text : Randall likes to speculate what the world would look like if humans could see radio waves, gamma waves, etc. Such a thought experiment would be pretty abstract due to the total lack of a frame of reference (since everything outside the visible light spectrum is by definition invisible and thus beyond human optical perception), but for many people, that's also what makes it enticing. Randall immediately turns this profound train of thought around with a crude joke that he wants to know what the viewer's sister would look like in the nude, an activity for which x-rays would be useful. [Everything is one big panel.] The Electromagnetic Spectrum These waves travel through the electromagnetic field. They were formerly carried by the aether, which was decommissioned in 1897 due to budget cuts. Other waves: Slinky waves [Cueball and Megan hold the ends of a tangled slinky.] Sound waves [There is a snippet of a frequency band. Between 20 Hz and 20 KHz is labeled "Audible Sound." Towards the top is a line labeled "That high-pitched noise in empty rooms."] The wave [A row of people does a wave.] [Three parallel scales are across the bottom. The first is lambda (m), ranging from 100Mm to 100fm; second is f (Hz), which starts at 1 Hz and reaches 100 THz about 2/3 of the way along, after which the labels read "other entertaining greek prefixes like peta- exa- and zappa-;" last is Q (Gal^2/Coloumb), whose labels are 17, 117, pi, 17, 42, phi, e^pi-pi, -2, 540^50, and 11^2. Above the scales and lined up accurately with the first two are the following:] Power & Telephone (100Mm to 1km) Radio & TV (1km to somewhere between 1m and 10cm); above that are many boxes showing subranges (AM, VHF, UHF, 24/7 NPR pledge drives, a very thin band for the space rays controlling Steve Ballmer, 99.3 "The Fox," 101.5 "The Badger," 106.3 "The Frightened Squirrel," cell phone cancer rays, CIA, ham radio, kosher radio, shouting car dealership commercials.) Microwaves (a bit more than 10cm to a bit more than 1mm); it also has subranges (aliens, just below SETI, wifi, FHF, brain waves, sulawesi, gravity) Toasters (about 1mm to about 100 micrometers) IR (about 100 micrometers to somewhere between 1 micrometer and 1 nm); above that is a bell graph labeled "Superman"s heat vision," with a motorcycle driving up the left side labeled "Jack Black's Heat Vision." Visible light (and, under it, visible dark); above that is a bell graph labeled "sunlight." There's a breakout chart above it showing the visible spectrum from 700nm (red) to 450nm (violet). There's an arrow pointing to where octarine would be, somewhere off to the side. Above that are bars showing the absorption spectra for hydrogen, helium, Depends(R) (yellow only), and Tampax(R) (red only). UV (about 100nm to about 10nm) Miller Light (a thin bar around 10nm) An unlabeled section with a thin line above it showing the frequency of the main death star laser A blocked-off portion labeled "Censored Under Patriot Act." X-rays (from about 1nm to about 10pm); a line above shows the frequency of mail-order x-ray glasses. Somewhere vaguely above the 10pm mark is a potato. Gamma/cosmic rays (10pm and smaller); above that is a bar marked Sinister Google Projects that also trails off into higher frequencies, and blogorays, which are slightly lower.

With Apologies to The Who

With Apologies to The Who

https://www.xkcd.com/274

https://www.explainxkcd.com/wiki/index.php/274:_With_Apologies_to_The_Who

[Cueball is sitting at a desk with a computer, typing.] Monitor: People try to shut us d-d-down just 'cause our music gets around [Cueball is standing on his chair and typing with his keyboard across his hip.] Monitor: Old folks act like total noobs get off our net; you block the tubes [Cueball is really wailing on the keyboard.] Monitor: Why don't you all just d-d-disconnect and don't try an' grok our d-d-dialect [Cueball smashes the keyboard into the monitor.] Monitor: I'm not tryin' to cause a big s-s-sensation I'm just bloggin' 'bout my generation The song was actually written by guitarist Pete Townshend . Roger Daltrey's name is misspelled as "Daltry".

This comic refers to the song " My Generation " by the British rock band The Who , which was released in 1965. The song is about intergenerational conflict and has been regarded as a very decided proclamation of youthful rebellion. Cueball adapts the lyrics to describe his own generation, the Millennials . As people born from the 1980s onwards grew up with the internet, this generation is also nicknamed " digital natives ." It is therefore natural that the updated lyrics should refer to blogging and internet slang . The actions performed by Cueball while typing the text relate to the original music video, in which The Who smash their instruments in true rock star fashion. Cueball wails his keyboard like a guitar and smashes his monitor in the end. The title text jokingly suggests that the band's lead singer Roger Daltrey originally meant the line And don't try and Digg what we all s-s-say as a reference to the social news site Digg , but changed it after switching to its competitor Reddit . Explanation of Terms An explanation of the terms in this comic: "noobs" is a synonym of "newbie," which is a person who is new to an online community and is thus often not familiar with the rules and norms of the community. Cueball is suggesting that old people are not competent/familiar with the online realm. "the tubes" is likely a reference to the saying series of tubes . "grok" is a synonym for "understand." Cueball is suggesting that people of older generations have difficulty understanding internet slang, which is often true. "bloggin'" (blogging) is the act of writing in a blog . Original Lyrics The original lyrics of the song run as follows: People try to put us d-d-down Just because we get around Things they do look awful c-c-cold I hope I die before I get old [...] Why don't you all f-fade away And don't try and dig what we all s-s-say I'm not trying to cause a big s-s-sensation I'm just talkin' 'bout my g-g-g-generation [Cueball is sitting at a desk with a computer, typing.] Monitor: People try to shut us d-d-down just 'cause our music gets around [Cueball is standing on his chair and typing with his keyboard across his hip.] Monitor: Old folks act like total noobs get off our net; you block the tubes [Cueball is really wailing on the keyboard.] Monitor: Why don't you all just d-d-disconnect and don't try an' grok our d-d-dialect [Cueball smashes the keyboard into the monitor.] Monitor: I'm not tryin' to cause a big s-s-sensation I'm just bloggin' 'bout my generation The song was actually written by guitarist Pete Townshend . Roger Daltrey's name is misspelled as "Daltry".

Thoughts

Thoughts

https://www.xkcd.com/275

https://www.explainxkcd.com/wiki/index.php/275:_Thoughts

[Cueball talking with his girlfriend's parents represented by Blondie, holding a hand up in greeting and a larger version of Cueball. Above them there is a caption:] When meeting a girlfriend's family, I have to suppress the weirdest thoughts. Cueball: Hi! Blondie: Hi! It's so nice to finally meet you! Cueball: I have licked your daughter's nipples.

This comic relates to the situation of getting introduced to the parents of one's girlfriend, which is often felt to be rather awkward. The parents tend to scrutinize and question the aspirant in order to find out if he is a good catch. A particularly delicate issue is the fact that the suitor may have had sexual intercourse with their daughter. This topic is almost never openly addressed, but can sometimes be felt in the subtext of the conversation. This makes the scenario somewhat susceptible to a so-called Freudian slip . The term describes a common psychological phenomenon where a subconscious thought bursts through and induces e.g. a slip of tongue. In the comic, Cueball tries to repress any thoughts of sexual nature while talking to her parents Blondie and Blondie 's Cueball-like man. He promptly utters the sentence "I have licked your daughter's nipples." and thus involuntarily addresses the topic he tried to avoid. The title text suggests that either the parents do not want their daughter to meet him again, or that the girlfriend interdicts his licking her nipples again because of the embarrassing scene. [Cueball talking with his girlfriend's parents represented by Blondie, holding a hand up in greeting and a larger version of Cueball. Above them there is a caption:] When meeting a girlfriend's family, I have to suppress the weirdest thoughts. Cueball: Hi! Blondie: Hi! It's so nice to finally meet you! Cueball: I have licked your daughter's nipples.

Fixed Width

Fixed Width

https://www.xkcd.com/276

https://www.explainxkcd.com/wiki/index.php/276:_Fixed_Width

[A man, Rob, is sitting at a computer. The text is an IRC-style transcript of a conversation, in a fixed-width font. He is text-messaging a girl he slept with named Emily; their messages read as follows:]

Fixed width or monospaced font refers to the font used in old teletype terminals and some instant messaging clients (often Courier ). For two text lines to have the same length, it's easier if they are in a monospaced font. For example, the following sentences are the same length in a monospaced font, but since we are using a proportional font , those lengths are not exact (the third line is noticeably wider): <rob> last night was nice <emily> the best i've had <rob> yeah it was AMAZING The title is possibly a double reference, both to a monospaced font and to lines of the same length. Initially, by mere chance, Emily's and Rob 's lines were exactly the same length. This made Rob want to continue the pattern. That Rob feels forced to change what he wants to type to continue the pattern could be a symptom of obsessive–compulsive disorder . Because of the monospaced font, any reply with 19 characters (including space) would have continued the pattern. In particular, "definitely for real" or "i'm in love with you" would have worked. In the title text Rob continues to write a sentence: "I wish I knew how to quit this so I wouldn't have to quit you." He acknowledges that he has a problem, since he cannot quit his desire to keep the fixed width. If he could have quit this desire, then he would not have had to quit Emily. But since he felt he had to keep the fixed width, he involuntarily wrote something that felt for Emily as if he quit her. And he was too late out with his apology for her to read it. [A man, Rob, is sitting at a computer. The text is an IRC-style transcript of a conversation, in a fixed-width font. He is text-messaging a girl he slept with named Emily; their messages read as follows:]

Long Light

Long Light

https://www.xkcd.com/277

https://www.explainxkcd.com/wiki/index.php/277:_Long_Light

[Cueball in a car, sitting at a red light.] Cueball: This light always takes forever. I'd like to smack the idiot who designed this intersection. [An engineer steps up onto the hood of Cueball's car.] Engineer: Hi. Cueball: Who the hell are you? Engineer: I designed this intersection. Engineer [arms spread outward]: You're right - I should have just made the light shorter! Never mind the hours of simulation and testing I did. Never mind that this intersection interacts with it's neighbors in a complicated way and it took me a week to work out timing sequences that avoided total jams. Engineer: Clearly, I'm a crappy engineer and you have a better solution. Go on, show me your proposed timings. Cueball: Get the hell off my hood before I start driving and fling you into traffic. Engineer: You can't. Light's red. Cueball: Well, when will it change? Engineer: Tuesday.

This strip depicts a common experience to most people - becoming frustrated with a device, system, or rule that appears to be badly made or have no purpose other than to frustrate the user (in this case, a traffic light that seems unreasonably, inexplicably long). One temptation we might have in these cases is to blame the designer of the system. Here, the designer appears and testifies to the amount of effort that went into the design, considering many factors. He challenges Cueball to come up with a better solution, the implication being that without a similar amount of training and effort, any naive solution would have flaws the designer would be happy to point out. This demonstrates to Cueball and the reader that just because they were unlucky enough to encounter something in a way that was inconvenient for no obvious reason, doesn't mean there is no reason at all. Of course, all of this has occurred after the designer leapt out of nowhere onto the hood of the car, so he may not be entirely stable. This is elaborated upon in the final panel, where the designer finally admits that red light won't change until Tuesday, but since this comic was published on a Friday, the timing scheme really was absurd after all. It is also possible that the designer has intentionally changed the light specifically to make Cueball wait for a couple of days, or to stop himself from being flung off of the hood of the car. The title text returns to the original point, reminding us that designers work hard and often encounter complex problems in doing their jobs. Their frustration may also be in part from the knowledge that future users will blame them for unavoidable problems and undervalue their work. With a little empathy, we can find a human connection to these problems, rather than let them drive us crazy. Randall returns to the theme of the unseen contributions of engineers in 1741: Work . [Cueball in a car, sitting at a red light.] Cueball: This light always takes forever. I'd like to smack the idiot who designed this intersection. [An engineer steps up onto the hood of Cueball's car.] Engineer: Hi. Cueball: Who the hell are you? Engineer: I designed this intersection. Engineer [arms spread outward]: You're right - I should have just made the light shorter! Never mind the hours of simulation and testing I did. Never mind that this intersection interacts with it's neighbors in a complicated way and it took me a week to work out timing sequences that avoided total jams. Engineer: Clearly, I'm a crappy engineer and you have a better solution. Go on, show me your proposed timings. Cueball: Get the hell off my hood before I start driving and fling you into traffic. Engineer: You can't. Light's red. Cueball: Well, when will it change? Engineer: Tuesday.

Black Hat Support

Black Hat Support

https://www.xkcd.com/278

https://www.explainxkcd.com/wiki/index.php/278:_Black_Hat_Support

[Black Hat is sitting at his computer, wearing a phone headset.] Black Hat: Thank you for calling the Black Hat Support Line, your first source for Linux support. How may I assist? Phone: Hi. I'm running an Apache server, and the load keeps climbing out of control. Black Hat: Okay. First, click on the Start Menu. Phone: I'm sorry, this is the Linux helpline, right? Black Hat: Of course, sir. Black Hat: If you'll just open the "My Documents" folder- Phone: Just a damn minute. I think you're putting me on. Black Hat: Please bear with me, sir. Black Hat: Now, load up your AOL and go to the Keyword "Linux"- Phone: *click*

This strip portrays Black Hat providing support for Linux , but in fact he provides only annoying and unhelpful advice just for his own personal amusement. The support line is clearly for Linux, as stated in the introduction, and the client on the phone clearly has a Linux problem. However, Black Hat is intentionally giving irrelevant instructions that refer to the Windows OS (Start Menu, My Documents Folder). Finally, Black Hat asks the client on the phone to "bear with him" and suggests that the client should use a highly obsolete mechanism to look for the answer to his problem, namely AOL keywords. AOL is well known for producing one of the earlier online communities and has since fallen largely out of favor. The client hangs up the phone. The title text mentions the function select() , which allows you to write asynchronous IO access routines by checking if it is ready to be read/written to at a specific moment. This is different than a threaded model, in that it can happen in a single thread. The danger of such programming is that if you do not coordinate the reader/writer properly, you can create a deadlock, which can result in the consumption of a lot of resources. [Black Hat is sitting at his computer, wearing a phone headset.] Black Hat: Thank you for calling the Black Hat Support Line, your first source for Linux support. How may I assist? Phone: Hi. I'm running an Apache server, and the load keeps climbing out of control. Black Hat: Okay. First, click on the Start Menu. Phone: I'm sorry, this is the Linux helpline, right? Black Hat: Of course, sir. Black Hat: If you'll just open the "My Documents" folder- Phone: Just a damn minute. I think you're putting me on. Black Hat: Please bear with me, sir. Black Hat: Now, load up your AOL and go to the Keyword "Linux"- Phone: *click*

Pickup Lines

Pickup Lines

https://www.xkcd.com/279

https://www.explainxkcd.com/wiki/index.php/279:_Pickup_Lines

[Cueball at a bar.] Cueball: If I could rearrange the alphabet, I'd put your sister and I together. Cueball: Is your father a thief? Because that's totally my Jetta you parked outside. Cueball: You must be tired, 'cause you've been running through my mind all night. Cueball: Screaming.

This comic adds strange twists to some classic abysmally cheesy pickup lines . Warning, terrible puns ahead: Cueball is making a "your sister" joke. A different variation of this line is featured in 1069: Alphabet . A Jetta is a car, and Cueball is implying that the father is an actual thief. He adds the word "Screaming," to make the word "running" be literal instead of figurative. This is yet another example of Beret Guy 's bartender job. The title text refers to a pickup line like this: "That shirt looks good on you, but would look even better on my bedroom floor." But here the shirt is used as fuse for a Molotov cocktail thrown into their office. [Cueball at a bar.] Cueball: If I could rearrange the alphabet, I'd put your sister and I together. Cueball: Is your father a thief? Because that's totally my Jetta you parked outside. Cueball: You must be tired, 'cause you've been running through my mind all night. Cueball: Screaming.

Librarians

Librarians

https://www.xkcd.com/280

https://www.explainxkcd.com/wiki/index.php/280:_Librarians

[Caption at the top:] Advantages to dating librarians. [Megan and Cueball are standing together; Cueball is reaching inside a paper bag:] Megan: We're stopping in Baltimore to visit my family, and that's final. Cueball: Oh yeah? [Cueball is upright and is holding a book.] Cueball: Hey, look, it's a new hardback book! Megan: You wouldn't. [Cueball bends the book backwards.] Book: crinkle [Cueball bends it back further.] Book: creak Megan: twitch [Cueball bends the book back still further.] Book: crack Megan: OKAY! Megan: You win!

Cueball is pressing on Megan for stopping her idea to visit her family. While Megan is fully convinced that this visit will happen, Cueball takes advantage of her love of books. He starts to open up a brand-new hardcover book much farther than it was made to open, ruining the spine, and then mistreats it some more. Megan cannot take this anymore, and gives up on the family visit. The title text goes on with the inflexible stereotype, as librarians will not make exceptions for or give reductions to their romantic partners' overdue fees. Alternately, it could mean that a librarian who is faced with the abuse of books as a bargaining tool would take retribution by not making an exception for late fees for their partner, particularly if said partner is absent-minded or otherwise disorganized. The humor comes from the stereotype of librarians as very sensitive to proper treatment of books and inflexibility with rule-breaking. [Caption at the top:] Advantages to dating librarians. [Megan and Cueball are standing together; Cueball is reaching inside a paper bag:] Megan: We're stopping in Baltimore to visit my family, and that's final. Cueball: Oh yeah? [Cueball is upright and is holding a book.] Cueball: Hey, look, it's a new hardback book! Megan: You wouldn't. [Cueball bends the book backwards.] Book: crinkle [Cueball bends it back further.] Book: creak Megan: twitch [Cueball bends the book back still further.] Book: crack Megan: OKAY! Megan: You win!

Online Package Tracking

Online Package Tracking

https://www.xkcd.com/281

https://www.explainxkcd.com/wiki/index.php/281:_Online_Package_Tracking

Online Package Tracking: Pros: Convenient, Useful Cons: Makes you crazy [Megan is sitting at a computer.] *refresh* Megan: Aww, still in Memphis. *refresh* Megan: Aww, still in Memphis. *refresh* Megan: Aww, still in Memphis.

Randall notes that package tracking, as provided by many shipping companies like UPS and FedEx Express , is helpful, as customers can see the status of their package delivery, and most people are very excited in the expectation of a package as shown in comic # 576 . However, Megan refreshes the package tracking page every few minutes in her impatience on the status of her package; it drives her crazy. The headquarters of FedEx Express are located in Memphis, and it also serves as its global "SuperHub" located at Memphis International Airport . The title text refers to the various " x of the month clubs" (fruit, cheese, wine, etc.) that one might have signed up for, only to receive a gift. But you are often not really interested in these gifts, and probably even less interested in receiving a stinging insect each month. This, combined with the ease by which a person can track the package, creates a strange dichotomy whereby you don't really want the package, but you keep checking where it is just because you can. Online Package Tracking: Pros: Convenient, Useful Cons: Makes you crazy [Megan is sitting at a computer.] *refresh* Megan: Aww, still in Memphis. *refresh* Megan: Aww, still in Memphis. *refresh* Megan: Aww, still in Memphis.

Organic Fuel

Organic Fuel

https://www.xkcd.com/282

https://www.explainxkcd.com/wiki/index.php/282:_Organic_Fuel

[Cueball at a computer and a friend standing nearby.] Cueball: Wow – Engines can burn vegetable oil. Friend: Well, sure. You can burn most any organic matter. Corns, leaves, spices... Cueball: Spices? Really? Friend: Sure – Mussolini made the trains run on thyme. Cueball: ... Cueball: We are no longer friends.

Cueball is fascinated about engines that can burn organic matter. But in fact, biofuel is a big industry today. It is criticized now and then, because it can affect food prices and is believed to exacerbate world hunger. Next comes a reference to the famous quote, "Mussolini made the trains run on time," an oft-quoted piece of propaganda from Italy under Fascist dictator Benito Mussolini . The pun is made on the fact that thyme (an herb, or as in this comic, a spice) and time (the universal phenomenon, as in the original quote) are homophones . But the organic matter thyme could technically be used as fuel. The title text may be interpreted in one of two ways. It may be attributed to the pun-maker, in which case he makes no apology for his corny joke, or it may be attributed to Cueball, in which case he makes no apology for the termination of friendship, since the pun was too terrible. Randall later made another joke on the fact that thyme and time are homophones: 1123: The Universal Label . [Cueball at a computer and a friend standing nearby.] Cueball: Wow – Engines can burn vegetable oil. Friend: Well, sure. You can burn most any organic matter. Corns, leaves, spices... Cueball: Spices? Really? Friend: Sure – Mussolini made the trains run on thyme. Cueball: ... Cueball: We are no longer friends.

Projection

Projection

https://www.xkcd.com/283

https://www.explainxkcd.com/wiki/index.php/283:_Projection

[Cueball and Megan are seated on a couch, watching TV.] Megan: Argh, movie pet peeve- Someone sitting at a computer in the dark with the screen projected on their face. Monitors don't work like that! [Cueball and Megan face each other on the couch.] Cueball: Right - that only happens if you're in the way of a projected image. Like when we're sitting together in a parked car in the rain and the mottled light through the raindrops on the windshield makes shifting shadows on your skin... [Beat panel.] [Megan stands up, Cueball uses a laptop on table behind the couch.] Megan: ...I wasn't really into the movie anyway. Cueball: The nearest rainstorm's about 60 miles away. Megan: We'll drive fast. Cueball: I'll grab some snacks.

Cueball and Megan are watching a movie on a couch. During the movie, a scene features a character's face with legible text projected by the monitor. Though commonly depicted for dramatic effect, this phenomenon does not actually occur with conventional monitor technology. Megan is annoyed and agitated by the inaccuracy of the effect. Cueball agrees and delves more into the optical underpinnings of projected images, but in the process segues into a romantic memory of the two of them in a parked car in the rain. At that point, the two lose interest in the movie and begin making preparations to drive to the nearest rainstorm for another romantic evening experience. This was the second time in four months that Randall mentions Pet Peeves . The first was 238: Pet Peeve 114 . The next, 1138: Heatmap , did not appear until more than five years later. [Cueball and Megan are seated on a couch, watching TV.] Megan: Argh, movie pet peeve- Someone sitting at a computer in the dark with the screen projected on their face. Monitors don't work like that! [Cueball and Megan face each other on the couch.] Cueball: Right - that only happens if you're in the way of a projected image. Like when we're sitting together in a parked car in the rain and the mottled light through the raindrops on the windshield makes shifting shadows on your skin... [Beat panel.] [Megan stands up, Cueball uses a laptop on table behind the couch.] Megan: ...I wasn't really into the movie anyway. Cueball: The nearest rainstorm's about 60 miles away. Megan: We'll drive fast. Cueball: I'll grab some snacks.

Tape Measure

Tape Measure

https://www.xkcd.com/284

https://www.explainxkcd.com/wiki/index.php/284:_Tape_Measure

[Cueball finds a tape measure.] Cueball: Hey, a tape measure. [Cueball extends the tape measure.] extend extend [The tape measure falls.] clatter [Cueball tries again.] click schwoop extend extend extend Cueball (thinking): Ooh, eight feet. I wonder if that's a record. [Cueball imagines an olympic stadium, with three people extending tape measures] Audience: Gooo! Goooo! Gooooooo!

Cueball acts like a small boy, finding a tape measure and then playing with it. He then extends it to 8 feet (approx. 2.5 meters), wondering whether or not that was a record, which makes him imagine a sport where extending the tape measure as far as possible was the goal. (Tape measure strips are bent upward lengthwise to support itself when oriented correctly, much like how one can better hold a sheet of paper horizontally by creating a slight dip. However, as a tape measure is extended, the weight of the strip eventually overcomes the support offered by the bend, causing it to collapse. Skillfully holding the tape measure at an angle can redirect some of the weight load and allow for a longer total extension; it is implied that this technique can be explored to the point of becoming its own sport.) The title text refers to a future where this sport exists, and this comic is a representation of the origin of this sport. [Cueball finds a tape measure.] Cueball: Hey, a tape measure. [Cueball extends the tape measure.] extend extend [The tape measure falls.] clatter [Cueball tries again.] click schwoop extend extend extend Cueball (thinking): Ooh, eight feet. I wonder if that's a record. [Cueball imagines an olympic stadium, with three people extending tape measures] Audience: Gooo! Goooo! Gooooooo!

Wikipedian Protester

Wikipedian Protester

https://www.xkcd.com/285

https://www.explainxkcd.com/wiki/index.php/285:_Wikipedian_Protester

[A man with dark flat hair is standing at a podium. He is speaking to a crowd while standing behind a lectern. The lectern has a microphone on the top and sports an American flag in color on the side. He holds an arm on the lectern and the other arm is held up in front of him with a finger pointing upwards. There are four red stars on the side of the podium below him and behind him something that could be high curtains. There is an empty gap between the podium and the first people in the crowd followed by a stick with a red top, that indicates a fence to keep the crowd at a distance from the podium. After the fence there is a large crowd of people listening, most of them only partly drawn, only a few has hair. Three signs can be seen above the heads of the crowd, but they are all empty white signs. Except in the middle of the crowd, where Cueball has been raised above the rest of the crowd. He is holding a large sign up over his head in both hands. The sign has a blue text in black square brackets:] [ Citation needed ]

Cueball holds up a sign reading "[ Citation needed ]" during a political speech. The sign text is based on the Wikipedia template that can be placed next to statements that need citations, (that look like this [ citation needed ] ) usually because of questionable validity. Cueball is using this template to challenge the politician's speech, as political speakers often throw out claims that are not real. The title text below the comic, “Semi-protect the constitution”, represents an alternative sign the protester could be holding. It is a pun on an occasionally-heard phrase “protect the Constitution,” which urges politicians to pass and enforce laws in a way that preserves the rules and rights set down by the U.S. constitution . “semi-protect” references semi-protection , a protection measure applied to some articles on Wikipedia, which protects some articles from being edited anonymously. More specifically, it does not allow articles to be edited by people who have been on the wiki for less than 4 days or made less than 10 edits unless an administrator or event coordinator manually confirms them earlier. Semi-protection on an article is shown by displaying this lock on the top right of an article. Constitutional amendments cannot usually be proposed anonymously. [1] [2] , meaning that in effect, all articles of the Constitution are semi-protected. [A man with dark flat hair is standing at a podium. He is speaking to a crowd while standing behind a lectern. The lectern has a microphone on the top and sports an American flag in color on the side. He holds an arm on the lectern and the other arm is held up in front of him with a finger pointing upwards. There are four red stars on the side of the podium below him and behind him something that could be high curtains. There is an empty gap between the podium and the first people in the crowd followed by a stick with a red top, that indicates a fence to keep the crowd at a distance from the podium. After the fence there is a large crowd of people listening, most of them only partly drawn, only a few has hair. Three signs can be seen above the heads of the crowd, but they are all empty white signs. Except in the middle of the crowd, where Cueball has been raised above the rest of the crowd. He is holding a large sign up over his head in both hands. The sign has a blue text in black square brackets:] [ Citation needed ]

All Your Base

All Your Base

https://www.xkcd.com/286

https://www.explainxkcd.com/wiki/index.php/286:_All_Your_Base

[A section of a Linux terminal window is shown.] Text from window: [Ponytail is at a computer.] Ponytail: What's with the All Your Base stuff? Didn't that die like five years ago? [From off-panel]: Yes. [Cueball enters the panel.] Cueball: It was my first internet meme, and my favorite. Others tired of it, but I never did. Cueball: So I wait. [Cueball raises his fists.] Cueball: Someday, decades from now, people will have forgotten. It will be fresh again. Cueball: Retro. Cueball: And when that day comes, Cueball: I WILL BE READY! Ponytail: You need a hobby or something. Cueball: What you say!! Cueball: Wait, too soon.

The comic refers to a popular internet phenomenon ( meme ) called " all your base are belong to us ." This catchphrase originated from the arcade shooter game " Zero Wing " and is a popular example of a poor translation into the English language. The phrase was popularized throughout the Internet and referenced in various images and videos. It is considered one of the earliest Internet memes, with the first occurrences dating back to the year 1998. Cueball has, according to the comic, participated in the spread of the meme during its heyday. Ponytail , examining Cueball's root directory, wonders at his keeping the content he created years ago, as the meme's popularity has decreased massively since then. Cueball answers that this was always his favorite meme, and that he is waiting for the day it gets revived. His second-to-last line, "What you say !! ," is a line from the game as well, although he says it much sooner than its supposed return to popularity. By using the example of internet memes, the comic also relates to the general principle of fashion , that everything once popular will, after a long enough time, be again in vogue. Trends experiencing this renaissance are often referred to as retro . Internet phenomena can be observed to follow the same rule, although with much shorter intervals due to the speed of information turnover. The title text prophesies the return of the "all your base" (AYB) meme in 2021 (similar-sounding to "AD 2101," the date mentioned at the beginning of the game). It also contains a pun on the term " zero hour " and the name of the game, which initially brought the phrase into fashion. The title text's prediction may have been recently fulfilled by Congresswoman Alexandria Ocasio-Cortez . [A section of a Linux terminal window is shown.] Text from window: [Ponytail is at a computer.] Ponytail: What's with the All Your Base stuff? Didn't that die like five years ago? [From off-panel]: Yes. [Cueball enters the panel.] Cueball: It was my first internet meme, and my favorite. Others tired of it, but I never did. Cueball: So I wait. [Cueball raises his fists.] Cueball: Someday, decades from now, people will have forgotten. It will be fresh again. Cueball: Retro. Cueball: And when that day comes, Cueball: I WILL BE READY! Ponytail: You need a hobby or something. Cueball: What you say!! Cueball: Wait, too soon.

NP-Complete

NP-Complete

https://www.xkcd.com/287

https://www.explainxkcd.com/wiki/index.php/287:_NP-Complete

My Hobby: Embedding NP-Complete problems in restaurant orders [A menu is shown.] Chotchkies Restaurant Appetizers Mixed Fruit 2.15 French Fries 2.75 Side Salad 3.35 Hot Wings 3.55 Mozzarella Sticks 4.20 Sampler Plate 5.80 Sandwiches Barbecue 6.55 [Megan, another person, and Cueball are sitting at a table. Cueball is holding the menu as well as a thick book and is ordering from a waiter. Megan is facepalming.] Cueball: We'd like exactly $15.05 worth of appetizers, please. Waiter: ...Exactly? Uhh... Cueball: Here, these papers on the knapsack problem might help you out. Waiter: Listen, I have six other tables to get to— Cueball: —As fast as possible, of course. Want something on traveling salesman?

Another entry in the " My Hobby " series of comics. Cueball is embedding NP-complete problems in restaurant orders. Specifically, he is ordering appetizers not by explicitly stating the names, but by the total price of them all. This is a simplified example of the knapsack problem . This is a problem in combinatorial optimization, as follows: If you have a knapsack (backpack or rucksack) that can hold a specific amount of weight, and you have a set of items, each with its own assigned value and weight, you have to select items to put into the knapsack so that the weight does not exceed the capacity of the knapsack, and the combined value of all the items is maximized. In computational complexity theory , NP stands for "nondeterministic polynomial time," which means that problems that are NP take polynomial running time (i.e. the time a CPU would take to run the program would be polynomial in the input size) to verify a solution, but it is unknown whether finding any or all solutions can be done in polynomial time. Polynomial time is considered efficient; exponential and higher times are considered unfeasible for computation. NP-complete problems are ones that, if a polynomial time algorithm is found for any of them, then all NP problems have polynomial time solutions. In short, particular guesses in NP-complete problems can be checked easily, but systematically finding solutions is far more difficult. The waiter's problem is NP-complete, since a given order's price can be found and checked quickly, but finding an order to match a price is much harder. This causes the order to effectively be an application layer denial-of-service attack / algorithmic complexity attack on the waiter, similar to Slowloris or ReDoS . (Formal proofs of the NP-completeness of the knapsack problem can be found at the above link.) The most straightforward way for a human to find a solution is to methodically start by first listing all the (6) ways of choosing one appetizer, and their total costs, then list all the (21) ways of choosing two appetizers (allowing repeats), and then list all the (56) ways of choosing three appetizers, and so forth. As any combination of eight appetizers would be more than $15.05, the process need not extend beyond listing all the (1715) ways of choosing seven appetizers. Another famous NP-complete problem is the travelling salesman problem , mentioned by Cueball at the end, referring to the waiter's claim that he has 6 more tables to get to. (see also 399: Travelling Salesman Problem ). The title text refers to the fact that NP-complete problems have no known polynomial time general solutions, and it is unknown if such a solution can ever be found. If the waiter can find an efficient general solution to this, he will have solved one of the most famous problems in mathematics. This problem is one of the six remaining unsolved Millennium Prize Problems stated by the Clay Mathematics Institute in 2000, for which a correct solution (including proving that such a solution doesn't exist) is worth US$1,000,000. A 50% tip is slightly less than fair. For those curious, there are exactly two combinations of appetizers that total $15.05 and solve the problem posed in the comic strip: My Hobby: Embedding NP-Complete problems in restaurant orders [A menu is shown.] Chotchkies Restaurant Appetizers Mixed Fruit 2.15 French Fries 2.75 Side Salad 3.35 Hot Wings 3.55 Mozzarella Sticks 4.20 Sampler Plate 5.80 Sandwiches Barbecue 6.55 [Megan, another person, and Cueball are sitting at a table. Cueball is holding the menu as well as a thick book and is ordering from a waiter. Megan is facepalming.] Cueball: We'd like exactly $15.05 worth of appetizers, please. Waiter: ...Exactly? Uhh... Cueball: Here, these papers on the knapsack problem might help you out. Waiter: Listen, I have six other tables to get to— Cueball: —As fast as possible, of course. Want something on traveling salesman?

Elevator

Elevator

https://www.xkcd.com/288

https://www.explainxkcd.com/wiki/index.php/288:_Elevator

[Elevator panel, with a Certificate of Inspection and five floor buttons, numbered 1–4. The fifth button is unlabeled.] [Cueball thinks.] [Cueball writes something on a small piece of paper.] Write Write [Cueball tapes it onto the panel.] [Elevator panel, with the same Certificate and buttons, and with the piece of paper labeling the fifth button "Zeppelin!"] [Cueball presses the new "Zeppelin!" button.] [Elevator moves.] Elevator: Ding [Cueball is looking out the door of a Zeppelin. The Zeppelin is flying over a green landscape with many lakes.]

Cueball is in an elevator, and notices that, beneath the certificate of Elevator Inspection , mandatory in all U.S. elevators at least, there are buttons for Floor 1, 2, 3, and 4, and then a mysterious unlabeled button. Possible logical conclusions he might have made include (1) there is a fifth floor reachable by pushing the bottom button which for some reason is not labeled; or (2) the button has some other function, a common one is to stop the elevator wherever it may be; or (3) the panel with the buttons is from a template used for various elevators with up to five floors, and as this particular elevator only goes to four floors, the bottom button is unlabeled, and nothing will happen if he pushes it. He has, however, chosen to believe in a different explanation: the fifth button is not currently assigned, but giving it a label will assign it to whatever floor or other function he can give it. The possibilities are truly endless. And so, the intrepid Cueball writes "Zeppelin!" on a slip of paper and tapes it next to the unassigned button, thereby assigning it to move the elevator not to Floor 5, but to a Zeppelin . And it works – the elevator opens aboard a Zeppelin floating in the air, high above a land with many lakes, perhaps Nunavut or other Northern Canadian tundra. The title text is most likely a reference to the Aerosmith song "Love in an Elevator," which really is about sex in an elevator. However, it would also be great if one could reach the elevation of love by getting there in a magic elevator. [Elevator panel, with a Certificate of Inspection and five floor buttons, numbered 1–4. The fifth button is unlabeled.] [Cueball thinks.] [Cueball writes something on a small piece of paper.] Write Write [Cueball tapes it onto the panel.] [Elevator panel, with the same Certificate and buttons, and with the piece of paper labeling the fifth button "Zeppelin!"] [Cueball presses the new "Zeppelin!" button.] [Elevator moves.] Elevator: Ding [Cueball is looking out the door of a Zeppelin. The Zeppelin is flying over a green landscape with many lakes.]

Alone

Alone

https://www.xkcd.com/289

https://www.explainxkcd.com/wiki/index.php/289:_Alone

[Megan crawling on bed toward Cueball.] Cueball: It's not something you can turn off. [Cueball pulling Megan, bedspread, and pillow off of bed onto floor.] Cueball: A part of me is always detached. Abstracting, looking at numbers and patterns. [Megan on top of Cueball, both under bedspread, on floor. Megan looks to be 'touching' Cueball.] Cueball: When we should be closest, part of me is still so alone. Counting the touches of her fingertips. Touch. Touch. Touch touch. Touch touch touch. Touch touch touch touch touch. [Same scene as third panel.] Cueball: Wait. Is that... That's the Fibonacci sequence! Whatever I did to deserve you, it couldn't have been enough.

Cueball is making love with Megan but, like many highly introverted people, his attention is split between his inner and outer worlds. Part of his mind is counting her touches, and another part is wondering why his brain does these things, automatically and without his wanting it to. This worries him, and he feels guilty because he isn't giving her his undivided attention, which he believes she deserves. As he unwillingly counts her touches, he recognizes the Fibonacci sequence . This recognition shocks him: it's like she knows what is going on in his head, and she sends him this signal to tell him that it's okay and that she understands. Awestruck, Cueball is reassured and glories in her love. The title text makes it clear that he is able to stop worrying about the counting and that he is able to let it continue just in the background. It doesn't stop, but it isn't nearly that important or salient as the touching done by Megan. [Megan crawling on bed toward Cueball.] Cueball: It's not something you can turn off. [Cueball pulling Megan, bedspread, and pillow off of bed onto floor.] Cueball: A part of me is always detached. Abstracting, looking at numbers and patterns. [Megan on top of Cueball, both under bedspread, on floor. Megan looks to be 'touching' Cueball.] Cueball: When we should be closest, part of me is still so alone. Counting the touches of her fingertips. Touch. Touch. Touch touch. Touch touch touch. Touch touch touch touch touch. [Same scene as third panel.] Cueball: Wait. Is that... That's the Fibonacci sequence! Whatever I did to deserve you, it couldn't have been enough.

Fucking Blue Shells

Fucking Blue Shells

https://www.xkcd.com/290

https://www.explainxkcd.com/wiki/index.php/290:_Fucking_Blue_Shells

My Profanity Usage By Cause: [A pie chart is shown.] [Injury is about 2.5% of pie chart.] [Irony is about 2.5% of pie chart.] [Misc is about 2.5% of pie chart.] [Segfaults is about 10% of pie chart.] [Mario Kart is about 82.5% of pie chart.]

Sometimes, something suddenly goes wrong, and you can only shout obscenities at it. For instance, when the dog bites, when the bee stings, something unexpected happens, or a program crashes (e.g. a segfault ), the victim often reacts by swearing. For Randall , however, profanities are caused mostly by blue shells in the video game Mario Kart . The blue shells, when fired, target the player currently in first place and stop them cold. In a close game near the end of the race, a player can go from first to an unrecoverable last in one hit. The title text refers to the " Double Dash " installment of Mario Kart. This includes a technique to avoid being hit by a blue shell, but it requires skillful timing to accomplish. The term " deep magic " comes from computer programmer slang. Interestingly, with a boost mushroom in Mario Kart Wii and Mario Kart 8 (and the so-called "Super-Horn" in the latter), it is also possible (with accurate timing) to escape blue shells. My Profanity Usage By Cause: [A pie chart is shown.] [Injury is about 2.5% of pie chart.] [Irony is about 2.5% of pie chart.] [Misc is about 2.5% of pie chart.] [Segfaults is about 10% of pie chart.] [Mario Kart is about 82.5% of pie chart.]

Dignified

Dignified

https://www.xkcd.com/291

https://www.explainxkcd.com/wiki/index.php/291:_Dignified

[Beret Guy swinging upside-down from a tree branch talking to White Hat walking by.] Beret Guy: You were once shoved headfirst through someone's vagina. Why are you acting so dignified?

Beret Guy is hanging upside down in a tree, usually something you might have done in your childhood. As an adult, it is not considered very dignified. Most likely, White Hat made a comment on this and the fact that Beret Guy has his head down. But then, Beret Guy gives him an answer, regarding where White Hat's head once came through and asks him why he is still acting so dignified . Here, Beret Guy is referring to the process of childbirth . Put in the way he mentions said process, the fact that White Hat came into this world in such a fashion would be very humiliating. In the title text, White Hat replies that he does not know, but then continues to ask why Beret Guy's beret stays on his head, even when upside down (in which gravity would tend to make a beret fall off). Beret Guy explains that he has stapled the beret onto his head. Such a process is similar to that of closing a wound after major head surgery, using surgical staples . Normally, the stapling of the head would be conducted with anesthetic and removed after the incision has healed, and only an insane person would do this to himself. Doing this the way Beret Guy did it would be very, very, painful, and likely a bad idea. [ citation needed ] Beret Guy is never seen without his hat (although it has been hidden under a green helmet once in 769: War ). And later in 478: The Staple Madness , it turns out that he likes to staple anything to everything, so maybe he also stapled his hat to his head. The staple madness comic may very well be a sequel to this comic 262: IN UR REALITY , where Black Hat implied that he had stapled stuff to cats in the title text. In the teaser trailer of Indiana Jones And The Last Crusade, Indy staples a hat to his head (or at least pretends to) to prevent it from blowing off, a similar situation to the one Beret Guy is in here. [Beret Guy swinging upside-down from a tree branch talking to White Hat walking by.] Beret Guy: You were once shoved headfirst through someone's vagina. Why are you acting so dignified?

goto

goto

https://www.xkcd.com/292

https://www.explainxkcd.com/wiki/index.php/292:_goto

[Sideways view of Cueball sitting at computer, thinking.] Cueball: I could restructure the program's flow - or use one little 'GOTO' instead. Cueball: Eh, screw good practice. How bad can it be? Text on computer: goto main_sub3; *Compile* [We now have a view from behind Cueball. Cueball looks at the computer.] [A raptor jumps into the panel, pushing Cueball off his chair.]

Goto is a construct found in many computer languages that causes control flow to go from one place in a program to another, without returning. Once common in computer programming, its popularity diminished in the 1960s and 1970s as focus on structured programming became the norm. Edsger W. Dijkstra 's article "Go To Statement Considered Harmful" in particular contributed to the decline of goto. Often, people learning programming are told that goto is bad and should be avoided, but frequently, they are not given a good reason. Cueball , as one of these people, sees no harm in using goto to avoid rewriting much of his program, most likely written in the C programming language. As a result, he is attacked by a velociraptor . Velociraptor attacks are a running joke (and fear) often expressed in xkcd . The name main_sub3 of the goto destination also shows bad programming style: it is an unmeaningful name suggesting that at least two similarly unmeaningful names are used for other goto marks and it is contradictory in that a chunk of code can either belong to the main program or to a subroutine, but not both. The title text refers to Neal Stephenson , an author of cyberpunk novels. A label is used in many programming languages to refer to a point in a program that a goto instruction can jump to. The joke is that one of Stephenson's characters in Cryptonomicon is named Goto Dengo. When said out loud, "Dengo" sounds like "Then go." [Sideways view of Cueball sitting at computer, thinking.] Cueball: I could restructure the program's flow - or use one little 'GOTO' instead. Cueball: Eh, screw good practice. How bad can it be? Text on computer: goto main_sub3; *Compile* [We now have a view from behind Cueball. Cueball looks at the computer.] [A raptor jumps into the panel, pushing Cueball off his chair.]

RTFM

RTFM

https://www.xkcd.com/293

https://www.explainxkcd.com/wiki/index.php/293:_RTFM

[Cueball with a knife sticking out of his heavily bleeding face stands in front of a toaster on a counter, which has an arm extending from the top of it. He is holding a telephone to his ear.] Cueball: Hello, 911? I just tried to toast some bread, and the toaster grew an arm and stabbed me in the face! 911: Did you read the toaster's man page first? Cueball: Well, no, but all I wanted was-- 911: click

The title RTFM is an acronym for " read the fucking manual ," which frustrated software manufacturers tell users when confronted with a simple question (most likely answered in the manual). However, Cueball encounters a similar situation with a 911 call (the emergency number in the US), in which the first question the 911 dispatcher asks is if Cueball has read the toaster's man page (man pages are the 'manual' for unix systems, but only describe commands and library functions, not hardware). Even if a man page existed, it is unreasonable to require the user of a toaster to read the manual simply to avoid being stabbed in the face. [ citation needed ] The 911 dispatcher decides that as Cueball has not read the man page, he is not entitled to medical assistance, and so hangs up. The title text refers to the popular phrase "Life's too short," which asserts that because we only have a limited amount of time on Earth, and that time can pass by quickly, we should make the most of it. That could mean, for example, don't spend time reading the documentation unless you actually experience a problem. The second part suggests that some people actually die because they didn't RTFM! [Cueball with a knife sticking out of his heavily bleeding face stands in front of a toaster on a counter, which has an arm extending from the top of it. He is holding a telephone to his ear.] Cueball: Hello, 911? I just tried to toast some bread, and the toaster grew an arm and stabbed me in the face! 911: Did you read the toaster's man page first? Cueball: Well, no, but all I wanted was-- 911: click

Bookstore

Bookstore

https://www.xkcd.com/294

https://www.explainxkcd.com/wiki/index.php/294:_Bookstore

[Cueball is standing in a bookstore, looking at a book.] Cueball [thinking]: This book looks interesting. Maybe I'll buy it. [Cueball reads the book; a clock appears above.] Cueball [thinking]: Oops, I read the whole thing. Cueball [thinking]: I'll just quietly put it back and go. [Cueball walks through a security scanner to exit the bookstore.] BEEP BEEP BEEP Voice from off-frame: Hey! Your brain set off the sensor! Cueball: I, uhh... Voice from off-frame: You have a book in there, don't you! Cueball: Crap.

Cueball starts reading a book off the shelf as he considers buying it, but gets so engrossed in it that he accidentally reads the entire thing, eliminating his reason for buying it in the first place. He quietly puts it back and turns to leave the store, only to have the book (which exists in his brain as information) set off the store's anti-theft sensor. This is a satire of copyright as it pertains to digital copies, because when you download a game or music file (or read a book, in this case), you are merely making an identical copy of the source material. The title text suggests that if the security guard wants to do a brain search, he might want to skip over all the presumably sexual encounters Cueball has had with the security guard's mom, thus inducing a 'yo mama' joke. [Cueball is standing in a bookstore, looking at a book.] Cueball [thinking]: This book looks interesting. Maybe I'll buy it. [Cueball reads the book; a clock appears above.] Cueball [thinking]: Oops, I read the whole thing. Cueball [thinking]: I'll just quietly put it back and go. [Cueball walks through a security scanner to exit the bookstore.] BEEP BEEP BEEP Voice from off-frame: Hey! Your brain set off the sensor! Cueball: I, uhh... Voice from off-frame: You have a book in there, don't you! Cueball: Crap.

DNE

DNE

https://www.xkcd.com/295

https://www.explainxkcd.com/wiki/index.php/295:_DNE

[Cueball is in an empty classroom writing on the whiteboard. In the top right corner in large print is written "Fuck This Place!". It is circled, and underneath he is writing "DNE".]

DNE stands for "do not erase," and is commonly used on school whiteboards to let the sanitation staff and other teachers know not to erase that particular area of the board. DNE circles often encompass important information such as test dates or the teacher's name. It is easy to see how leaving things marked with DNE can become automatic for anyone often erasing boards, so that they don't notice what the message actually says, or reflect on whether the DNE-marking is reasonable for it. Cueball 's dissatisfactory note is not very subtle, but Randall notes in the title text that advertisers have successfully used the same tactic for less conspicuous URLs to their sites. He also kindly asks you to replace those messages with xkcd.com to get some free advertising. On the bottom half of the board is a crossed out 2x2 matrix and two functions for exponential decay . [Cueball is in an empty classroom writing on the whiteboard. In the top right corner in large print is written "Fuck This Place!". It is circled, and underneath he is writing "DNE".]

Tony Hawk

Tony Hawk

https://www.xkcd.com/296

https://www.explainxkcd.com/wiki/index.php/296:_Tony_Hawk

My Hobby: Doing skateboard tricks in Tony Hawk while also doing them in real life. [Cueball moves towards a quarter pipe on his skateboard while manipulating his PSP.] Beep Click Beep [Cueball is in mid air having performed a Frontside 360°, both literally and on the PSP.] ♪ Frontside 360°! ♫ Frontside 360°!

Cueball is seen using a hand-held game system, while on a skateboard. He is playing one of the many Tony Hawk titles in which you control a skater and perform tricks to gain points and achievements. While playing the game, he wants to simultaneously perform the trick in real life, both because it is exceptionally difficult to do both and because the game will give him praise when he does a trick successfully. In the title text, Randall describes his Bad Idea #271: Dropping into the half-pipe on a Segway . One imagines this would result in the Segway becoming unstable and going completely crazy, hence one would classify it as a "bad idea." Which is surprisingly not the case; it even looks quite fun . The Segway engineers obviously foresaw this situation and implemented the Segway controller with its tilt sensors accordingly. My Hobby: Doing skateboard tricks in Tony Hawk while also doing them in real life. [Cueball moves towards a quarter pipe on his skateboard while manipulating his PSP.] Beep Click Beep [Cueball is in mid air having performed a Frontside 360°, both literally and on the PSP.] ♪ Frontside 360°! ♫ Frontside 360°!

Lisp Cycles

Lisp Cycles

https://www.xkcd.com/297

https://www.explainxkcd.com/wiki/index.php/297:_Lisp_Cycles

[Cueball is sitting at a computer, and Megan is standing behind the desk.] Cueball: Lisp is over half a century old and it still has this perfect, timeless air about it. Cueball: I wonder if the cycles will continue forever. A few coders from each new generation rediscovering the Lisp arts. [Man in Jedi robes carrying a towering stack of parentheses in his arms, speaking to Hairy.] Jedi: These are your father's parentheses. Elegant weapons. For a more... civilized age.

Lisp is one of the oldest high level programming languages . Despite being significantly ahead of its time, it never got enough traction outside of academia, and has never been widely used. However, it is considered to be a very powerful language even in the present day. Quotations regarding Lisp show that several big names in computer science and the tech industry hold Lisp in very high esteem. Eric S. Raymond goes as far as to say Lisp is also famous for its use of fully parenthesized Polish prefix notation . As a result, Lisp programs take the form of enormous nested lists bounded by parentheses, and it is not uncommon to see the source code of a large Lisp program close off with an equally enormous stack of close-parens, representing the simultaneous termination of dozens of recursively and hierarchically nested functional and procedural structures. In the first panel, Cueball praises Lisp, observing that no other language can match the awe that it still strikes despite its significant seniority. In the second panel, Cueball proposes that new programmers might continue to learn Lisp forever; despite the language's lack of widespread adoption, a small cadre of hackers will always exist who keep the language alive. The third panel references Star Wars . The "old wizard" Obi-Wan Kenobi, who remembers the culture and sophistication of the Old Republic ("Before the dark times. Before the Empire.") and lives as a hermit in the desert at the beginning of the film spoke these lines when passing on a lightsaber to Luke Skywalker: The title text is also a reference to Star Wars lines: The MIT mentioned in the title text is, of course, the Massachusetts Institute of Technology, an institution fundamental to the development of Lisp (and Scheme, which is a dialect of Lisp). For about 20 years, MIT taught Scheme in its introductory computer science course, 6.001 — Structure and Interpretation of Computer Programs (that course has since been replaced with a course teaching Python). [Cueball is sitting at a computer, and Megan is standing behind the desk.] Cueball: Lisp is over half a century old and it still has this perfect, timeless air about it. Cueball: I wonder if the cycles will continue forever. A few coders from each new generation rediscovering the Lisp arts. [Man in Jedi robes carrying a towering stack of parentheses in his arms, speaking to Hairy.] Jedi: These are your father's parentheses. Elegant weapons. For a more... civilized age.

Tesla Coil

Tesla Coil

https://www.xkcd.com/298

https://www.explainxkcd.com/wiki/index.php/298:_Tesla_Coil

[Cueball and Black Hat stand near a tesla coil mounted on a table.] Cueball: I finally finished my Tesla Coil! [The room is dark; the characters appear as faint blue outlines on black background. Cueball turns on the Tesla Coil and it sparks white static electricity.] click Black Hat: Cool, but— [Lightning shoots out of Black Hat's hands, Cueball appears to be in shock and awe.] Black Hat: Check this out! [The lights are back on, Cueball's arms are raised in amazement.] Cueball: How did you do that? Black Hat: The world doesn't actually make any sense. Science doesn't work. No one told you because you're so cute when you get into something. [Black Hat floats up the frame, and Cueball is pointing towards Black Hat.] Black Hat: Still, neat toy. Cueball: Now you're hovering! Black Hat: I guess you're still not getting this.

Cueball diligently creates a Tesla coil , a device that produces high voltage alternating currents. After that show by Cueball, Black Hat magically shoots electricity from his fingertips. When Cueball asks how he did that, he says that science doesn't really work, then hovers in mid-air, further proving his point. There is simply no apparent explanation for Black Hat's abilities, which means science is still woefully incomplete or, as Black Hat said, simply doesn't work. The title text indicates that this was all actually a dream, explaining Black Hat's abilities and pointing out how dreams can be difficult for scientists as they will attempt to analyse and understand everything in the dream according to the laws of science, which wouldn't apply in dreams. [Cueball and Black Hat stand near a tesla coil mounted on a table.] Cueball: I finally finished my Tesla Coil! [The room is dark; the characters appear as faint blue outlines on black background. Cueball turns on the Tesla Coil and it sparks white static electricity.] click Black Hat: Cool, but— [Lightning shoots out of Black Hat's hands, Cueball appears to be in shock and awe.] Black Hat: Check this out! [The lights are back on, Cueball's arms are raised in amazement.] Cueball: How did you do that? Black Hat: The world doesn't actually make any sense. Science doesn't work. No one told you because you're so cute when you get into something. [Black Hat floats up the frame, and Cueball is pointing towards Black Hat.] Black Hat: Still, neat toy. Cueball: Now you're hovering! Black Hat: I guess you're still not getting this.

Aeris Dies

Aeris Dies

https://www.xkcd.com/299

https://www.explainxkcd.com/wiki/index.php/299:_Aeris_Dies

[Two men are talking. The second man is sitting on the ground, hugging his knees to his chest.] Cueball: Maggie's gone. You can't bring her back. Friend: But I have to, she's a part of my life. Cueball: *sigh* Cueball: Okay, let me put this in your terms. Cueball: Remember when Aeris died in FFVII? It was sad, but you had to keep playing . Friend: Actually, I downloaded a mod to add her back to my party. It changed other character's appearances and dialogue to hers so you didn't have to lose her. Friend: Lots of gamers did it. [Cueball puts his hand on his chin.] Cueball: That is troubling on several levels. Friend: I wonder if Maggie's old dresses would fit you.

From the looks of this comic, there is a friend here who had a loved one (named 'Maggie') who died. Maggie is likely a spouse or girlfriend, but could also be a mother or another significant relation. Cueball tries to help him by comparing his plight to a significant plot point in the popular game Final Fantasy VII for the PlayStation 1 in 1997, the plot point being the permanent death of Aerith Gainsborough (originally translated as "Aeris"), the last of a race called 'the Ancients' and a potential love interest of the main character of the game. Although technically being a spoiler due to its significance and dissonance to the plot, Aerith's death became one of the most iconic video game scenes of all time, leading to its referencing and even parodies throughout the game community (some even depicting her revenge on Sephiroth , the main antagonist of the game and her murderer). The word 'permanent' was not meant for redundancy in the last paragraph; the developers wanted to symbolize how death is unexpected, leaving you with an empty feeling, filled only by regret. Therefore, when they received word about how much people wanted Aerith to be brought back to life, they felt that they succeeded with evoking the right feelings with her death. Even so, due to all the significance her death brought, the developers refused to officially resuscitate her. That did not stop other people from modifying the game in order to unofficially resuscitate her, though. Cueball feels really troubled that his friend would take such a course of action (especially with a fictional character, admittedly) instead of dealing with her death. His friend takes this to more disturbing levels, wanting to 'mod' Cueball with Maggie's clothes, turning Cueball into a 'substitute Maggie.' The title text references The Sims , a series of life simulation games where you can create virtual people (the aforementioned Sims), set their appearances, and essentially mess around with their lives. Cueball notes that his friend already attempted to 'recreate' Maggie and him (repeatedly at that) using the simulation abilities in the games of his The Sims series. [Two men are talking. The second man is sitting on the ground, hugging his knees to his chest.] Cueball: Maggie's gone. You can't bring her back. Friend: But I have to, she's a part of my life. Cueball: *sigh* Cueball: Okay, let me put this in your terms. Cueball: Remember when Aeris died in FFVII? It was sad, but you had to keep playing . Friend: Actually, I downloaded a mod to add her back to my party. It changed other character's appearances and dialogue to hers so you didn't have to lose her. Friend: Lots of gamers did it. [Cueball puts his hand on his chin.] Cueball: That is troubling on several levels. Friend: I wonder if Maggie's old dresses would fit you.

Facebook

Facebook

https://www.xkcd.com/300

https://www.explainxkcd.com/wiki/index.php/300:_Facebook

Mildly sleazy uses of Facebook, part 14: Looking up someone's profile before introducing yourself so you know which of your favorite bands to mention Cueball: Favorite bands? Hmm... Cueball: Maybe Regina Spektor or the Polyphonic Spree. Megan: Whoa, those are two of my favorites, too! Megan: Clearly, we should have sex. Cueball: Okay! My favorite position is the retrograde wheelbarrow. [Megan raises arms.] Megan: Ohmygod, mine too!

This comic approaches how Social networks have changed the ways of human interaction. With everyone placing their personal interests on their Facebook profile pages, it has become fairly easy to gather a lot of information about people. In the comic, Cueball uses this information to his advantage: He ascertained Megan's musical preferences beforehand in order to create the illusion of their sharing mutual interests. Megan is led to believe that he is like-minded , thus making it easier for Cueball to persuade her into having sex with him. Here the comic takes at the fact that many people use Facebook as a hunting ground for sexual contacts. Apparently, Megan did not only mention her favorite bands in her profile, but also her preferred sex position . This can be read as a sideswipe at what intimate details some people are willing to share on the internet. Although mentioning sexual preferences is hyperbolic here. Megan's taste in both fields can be regarded as outside the mainstream. Regina Spektor and The Polyphonic Spree are representatives of the indie pop genre. The Wheelbarrow ( NSFW ) features the man standing behind the woman and holding her legs, while she props up in a wheelbarrow-like position. The retrograde variant has the woman facing upwards. Unusual sex positions are also mentioned in comics 414: Mistranslations and 487: Numerical Sex Positions . The title text suggests that Cueball did not stop at reading Megan's interests on her Facebook profile, but also obtained her phone number and placed it in his phone. It is implied that some of the "mildly sleazy" uses of Facebook can border on the verge of stalking . When Megan discovers the number, she may realise this and stay clear of Cueball... Mildly sleazy uses of Facebook, part 14: Looking up someone's profile before introducing yourself so you know which of your favorite bands to mention Cueball: Favorite bands? Hmm... Cueball: Maybe Regina Spektor or the Polyphonic Spree. Megan: Whoa, those are two of my favorites, too! Megan: Clearly, we should have sex. Cueball: Okay! My favorite position is the retrograde wheelbarrow. [Megan raises arms.] Megan: Ohmygod, mine too!