Retconning the Wiki

A character edits a wiki - be it Wikipedia or any other free info source - and adds an information which is gibberish or they know to be false, to make a practical joke, to mislead someone who's been using this source without testing it, or just for the sake of it. Hilarity Ensues... but only for the person in question.

See also Wiki Vandal for info on people who actually do this in real life and ways to counter them.

Please note: no Real Life examples, unless they were directly caused by media.

Comic Strip

 * Bucky from Get Fuzzy edits Wikipedia to say that he won Wimbledon and that his "album" went "fourple platinum", as well as that he beat up Fungo.
 * In a great show of self-fulfilling prophecy, the comic strip FoxTrot mentions Jason vandalizing the Wikipedia article for "Warthog" by replacing the image with a picture of his sister Paige. This prompted some FoxTrot readers to go onto Wikipedia and replace the image with a picture of Paige.
 * One Dilbert cartoon has the character Topper make a string of implausible claims about his achievements. When the other characters ask for proof, he replies "Give me ten minutes, then check Wikipedia."

Live-Action TV

 * Stephen Colbert's "wikiality" on The Colbert Report.
 * A running joke on Talkin Bout Your Generation is Shaun Micallef quoting some 'facts' about the topic at hand he claims he got from Wikipedia, all of which are hilariously wrong.
 * On 30 Rock, Jenna was set to play Janis Joplin on a movie, so the guys vandalized the Wikipedia article on her to mess with Jenna and get her to do silly stuff.
 * Raj on The Big Bang Theory admits to vandalizing Wikipedia.

Music

 * The music video for Weird Al's song "White And Nerdy", in which he replaces the entire text for Atlantic Record's wiki page with huge type reading YOU SUCK!!!!! This was a personal Take That from Al for slights the company had done him in the past. His fans thought it was so funny, they started doing it for real, resulting in That Other Wiki having to lock the Atlantic Records page.

Webcomics

 * In Penny Arcade, both Tycho and Gabe. Gabe does that for fun, Tycho out of grudge.
 * There's also a strip where Skeletor can be seen vandalizing the He-Man and the Masters of the Universe page on Wikipedia... here
 * Dinosaur Comics suggests that we solve this problem on Wikipedia by only vandalizing the article about chickens, because "dudes already know about chickens."
 * One 8-Bit Theater strip implies that Black Mage vandalised Wikipedia to win an argument with Red Mage.
 * This was seen at least once in Shortpacked!.

Web Original

 * Dragon Ball Abridged's Frieza is apparently a Wiki Vandal, changing the Saiyan page to say "Stupid monkeys hit by falling rocks".
 * Replacing everything on Wikipedia's article on Earth with "Mostly Harmless." is a bannable offence, as that particular act of vandalism, inspired by a similar act in the book, except it was done by editors, was done way too many times.
 * "Wikipedia Brown and the Case of the Captured Koala." Changes to Wikipedia - basically vandalism - cause Wikipedia Brown angst, Rewriting Reality around him.
 * Superman edits Clark Kent's Wikipedia

Western Animation

 * American Dad: Steve once wrote an article about "Truth of peanut butter". Adding such information would probably also called vandalism.