In-joke

An in-joke or inside joke is a Joke whose Humour is clear only to those people who are in a group that has some prior knowledge (not known by the whole population) that makes the joke humorous.

This group of people could be, for example:

• a nuclear Family or (parts of) an extended family
• people of the same vocation or profession
• residents of a particular town or region
• students and/or alumni of a particular College or University
• viewers of a particular Television series or cult movie
• readers of a particular Book or series of books
• users of the same computer or computer software
• a group of friends or work colleagues
• practitioners of a particular craft, art, or science

In-jokes sometimes appear in film and television. Such jokes may be visual (for example, a movie theatre marquee shown in the background of a scene might display the title of one of the film director's other works), or delivered in dialogue. In-jokes can also take the form of homages to other films or television series.

It is often considered impolite or otherwise meaningless to share in-jokes among those who are not "in" on the joke, since any hope of a laughing response will depend on a careful explanation of the joke's circumstances, thereby diluting the joke's effect.

Examples

• Typos introduced by the typo fairy: Professional editors and writers
• Story ideas coming from a mail-order business in Schenectady, New York: Science fiction authors
• The Wilhelm scream, an in-joke among movie sound technicians
• Letting out the Magic smoke: among electrical engineers
• The Invisible Pink Unicorn, more or less the Mascot of many atheists, which symbolises the (in their eyes) absurdity of believing in a higher being; see also Flying Spaghetti Monsterism
• The motion picture Thunderbirds includes several references to puppets and marionettes, referring to the original television program's use of marionettes for its cast. (Most of these are subtle, though at one point the archvillain "The Hood," mentally controlling "Brains," remarks, "Like a puppet on a string!")
• The UnrealEd Goblin is a popular in-joke known by mappers and modders who use the UnrealEd tool, packaged with every successive version of Unreal-series games.
• Yoda's theme from Star Wars is featured in the soundtrack of E.T. as a child in a Yoda costume is seen by the titular alien. Both scores were composed by John Williams.
• Similarly, an unused version of the cue "The Planet Krypton" from Superman: The Movie included a statement of the Force Theme from Star Wars. Both scores were composed by John Williams Conversely, ET-like creatures were featured in the Senate scene in The Phantom Menace.
• /* You are not expected to understand this */ and Knuth's Forth volume for Computer scientists
• In Peter Jackson's Lord of the Rings films, the character Boromir played by Sean Bean, who played the title role in the Sharpe series, cuts himself on a broken sword and notes that it is "still sharp."
• Steven Spielberg served as executive producer for Gremlins and Back to the Future. The same backlot set was used to represent the cities in both films, and features a theater marquee with the titles "Watch the Skies" and "A Boy's Life," which were the respective working titles of Close Encounters of the Third Kind and E.T. the Extra-Terrestrial.
• In Spaceballs, during the transformation of the ship called, "Metamorphosis", Dark Helmet asked, "Ready, Kafka?" This is a reference to Jewish author Franz Kafka, who wrote a book of the same name, which is arguably the most famous of his works.
• In Star Trek: The Next Generation, several access panels contained tiny in-jokes (they were never legible on screen). Also, the main schematic of the Enterprise in engineering contained a mouse and a hamster on a treadmill.
• Uncyclopedia typically makes frequent references to Oscar Wilde, Steve Ballmer's hitlist , This Guy and Kitten Huffing, etc.
• In The Producers, in the title characters search for 'the worst play ever written,' one character reads a sentence about a man waking up one morning finding himself turned into a giant cockroach. The second character rejects it on the grounds that it is 'too good.' Despite the seemingly ridiculous content of the sentence, it is indeed 'too good:' it is the opening sentence to Franz Kafka's The Metamorphosis.
• The abreviation HFIL for the word hell among web-sites - originated from the edited Dragon Ball Z and later DBZ Uncensored.