Medium Shift Gag

So you're watching your favorite Saturday Morning Cartoon, all the bright and colorful characters are bouncing across the screen, and...oh hey, one of them is a puppet now. Or a clay-animated doll. Or a stop-motion figurine. Or a guy in a purposely bad costume.

This is the Medium Shift Gag, a joke that plays on the audience's expectations for a show to keep to a certain medium, but catches them by surprise when suddenly the world they've been witnessing is viewed through a strange and different new light, if only momentarily.

Differs from Medium Blending, which usually involves two or more different media constantly mixing together in the same work, while a medium shift gag involves a quick and abrupt change that's Played for Laughs.

Anime and Manga

 * FLCL: In two of the anime episodes, the art suddenly changes to manga style for a while.
 * There is also the scene where it shifts to South Park style animation for Amarao's haircut.

Film

 * Better Off Dead has a couple of gag sequences in clay animation, representing Lloyd Dobler's bizarre daydreams about dancing hamburgers and so forth.
 * In The Hitchhikers Guide to The Galaxy, after the Heart of Gold uses the infinite improbability drive, everything and everyone in the ship briefly turns into yarn. The actors are all replaced by stop-motion yarn figures for this gag.
 * In Horton Hears a Who, the previously All CGI Cartoon briefly shifts into more traditional 2D animation that mimics anime as Horton imagines himself as a ninja sworn to protect the tiny world on the clover.
 * Stay Tuned: Roy and Helen are Trapped in TV Land; at one point they're in a cartoon as mice.
 * When Jeff recounts the legend of Cthulhu in The Last Lovecraft: Relic of Cthulhu it switched to a comic-book style animation.

Live-Action Television

 * A Christmas special for Community was done in clay animation to go along with Abed's breakdown.
 * In a third season episode, when Jeff and Shirley get into a fight over foosball, their anger is expressed via an abrupt shift to an Animesque cartoon sequence.
 * Fringe did this unexpectedly. In one of the latest episodes of Season 3, it turned into a cartoon... because they couldn't get William Bell's actor to show up.
 * One episode of Home Improvement had a Dream Sequence done in clay animation.
 * Non-joke version (sort of) in Life On Mars, with a brief sequence of Sam Tyler and Gene Hunt as stop motion characters in a Camberwick Green sequence caused by the drugs Sam Tyler was being fed while in his coma.
 * In My Name Is Earl, Randy was given some drugs and saw the world in clay animation.
 * The full version of the musical number "Tongue Tied" from Red Dwarf includes a clay-animated sequence.
 * During the period it was part of Saturday Night Live, this was a feature of "TV Funhouse". More recently, one of the Digital Shorts had the characters from "TV Funhouse" segment "The Ambiguously Gay Duo" transformed into live-action versions of themselves.
 * Farscape did an episode where Crichton started hallucinating everything happening in a Looney Tunes Coyote and Road Runner type of cartoon.
 * Black Books at one point has all the characters turn into puppets. One DVD extra has a "mini-series" made completely of these puppets.

Western Animation
""Nosferatu!""
 * Chowder occasionally cuts to stop motion or puppetry for brief moments. One episode had a minotaur baby in Conspicuous CG, whose appearance freaked out the other characters out in an In-Universe example of the Uncanny Valley effect.
 * Family Guy:
 * In the "Road to the Multiverse" episode, Brian and Stewie find themselves in a dimension where they are a live-action dog and baby, and instead of commenting on it, they merely state that the universe scares them, and they immediately leave.
 * An earlier example occurs when Peter turns live action during a drug-induced Freak-Out.
 * The Star Wars episodes all have this.
 * The punchline of the Bugs Bunny cartoon "Rabbit Hood" is that Robin Hood has been MIA for most of the film, and when he finally appears, it's live-action footage of Errol Flynn from The Adventures of Robin Hood. A dumbfounded Bugs comments, "That's silly, it couldn't be him!"
 * The The Adventures of Jimmy Neutron/Fairly Oddparents crossover episode had fun with this. One character jumped back and forth between CGI and 2D animated "worlds", shouting, "I'm bulgy! Now I'm flat! I'm bulgy! I'm flat!"
 * The Simpsons:
 * In one segment in the 2010 Christmas Episode, everybody was a Muppet instead of a cartoon character.
 * In one Simpsons Halloween episode, Homer entered "the third dimension" and became CGI 3D, as did Bart when he went into that dimension to rescue Homer.
 * Another Halloween Episode had Bart and Lisa Trapped in TV Land, at one point interrupting The Regis and Kelly Show.
 * One episode had the opening re-enacted by live actors (actually a promo for Sky 1).
 * SpongeBob SquarePants:
 * The show occasionally shifts from a cartoon to a cheap puppet show. One episode in particular is "Pressure", in which SpongeBob, Patrick, Mr. Krabs, Squidward and Sandy all leave the ocean, and when they arrive on dry land...they are lousy toys or models propped up as puppets. The only exception, of which, is Squidward, whose puppet looks disturbingly like the actual Squidward.
 * There's also the classic scene in which Squidward wonders who was flickering the lights throughout an episode, and the camera shifts to see Nosferatu turning the lights on and off.


 * One episode of South Park featured a scene reshot in flashy CGI, to make fun of George Lucas adding CGI effects to the original Star Wars trilogy.
 * The episode "I Should Have Never Gone Ziplining" is presented as a documentary about the boy's disastrous field trip. At one point a disclamier card introduces a Dramatization of events and suddenly Stan, Kyle, Cartman and Kenny are live adult actors in a real boat filmed on a real lake.
 * There was an episode of Arthur that had South Park-style animation done for a segment.