Cartoon characters can survive a lot of things. And if a character ever suffers from the dreaded Anvil On Head, one of several things can happen. They can become an Accordion Man, or this trope can occur.
Often, characters will be Squashed Flat by some heavy object landing on their head, or by going really fast into an immovable object such as a wall, or a big and heavy character will squash a smaller character and leave them stuck to their bodies like Butt Stickers. The resulting injury has the character flattened down to a paper-thin state. While in this state, the character becomes incredibly light and can be lifted, manipulated, rolled up, or folded by another character.
These injuries are hardly ever fatal, and like most Amusing Injuries, are healed in just five seconds. Often, all it takes is another character flapping the flattened character around like a beach towel or inflating the character like a balloon to get him or her to return to his/her normal state.
Although this trope is mostly an Animation Trope, it sometimes creeps into live action shows with a more 'cartoonish' feel.
Can be the result of a Crush Parade when this trope is exaggerated.
Overlaps with Paper People, which is either a natural state of the characters or the state that results from being Squashed Flat. Not to be confused with Flat Character. Compare with Hammered Into The Ground.
In one episode, Escargon gets flattened as he is sent flying and hits a wall.
Pokémon had the episode Gluttonous Kabigon! Huge Panic! (or Snack Attack! in the English dub), in which Snorlax would roll over and lay on some of the Pokemon trying to attack him. The sight of a flattened Victreebel trying to walk around while flat, and shrieking at the top of its lungs, is hysterical.
This happens in KoiKoi7, where four girls are trampled flat in the anime.
One robber / rapist crushed by a millstone in a story by Wilhelm Busch. Other than typical for this trope, he doesn't exactly revert.
There's a Don Martin MAD cartoon where two guys discover a friend lying in the road, completely flat and stretched out. Naturally they conclude that he has been run over by a steamroller, and proceed to fold him up so they can take him to a hospital. Unfortunately due to a tragic misunderstanding involving a nearsighted strongman, he gets torn in half.
The Vault of Horror story "Graft In Concrete!" plays this lethally straight.
One of the junkyard robots becomes Crushed Flat in the Astro Boy 2009 movie.
Darla in Cats Don't Dance, who gets pressed into a table shape during the finale.
The pirate jackrabbit receives this in Ice Age: Continental Drift, upon being stepped on by Ellie. Scrat also gets stepped on by several large animals in the first movie, but doesn't exactly get flattened, per se.
Happens to a lot of toons in Who Framed Roger Rabbit, but especially Judge Doom, who is revealed to actually be a toon in the process. Eddie himself falls victim when riding in Droopy's express elevator.
A notable live-action version to go alongside the above is The Mask, after the masked Jim Carrey character jumps out the window of his apartment and lands on the street below.
Another cartoon-like example occurs in Space Jam, when Wayne Knight is crushed by all the Monstars.
Sleeper: The Leader of the futuristic dictatorship - or what's left of him - his nose ends up flattened under a steamroller.
Beetlejuice - an employee in the afterlife bureaucracy died as human roadkill - he's even got tire treads across his chest. He asks newcomers Adam and Barbara how he looks; they diplomatically say "Fine!" He replies "Thanks, I've been feeling a little flat!" and laughs at his own joke.
Austin Powers, driving a slow-moving steamroller, runs over one of Dr. Evil's henchman, who stands motionless in front of it, screaming in terror, for an absurd amount of time. A deleted scene on home video cuts to his wife at home, rolling a pie crust flat before receiving the news.
Q: What do you get if Batman and Robin get smashed by a steam roller? A: Flatman and Ribbon.
Caller: Hullo? Officer. I have to report an incident. A man has just been crushed by a steamroller. Police: We're on our way. The address of the incident? Caller: Somers Avenue ten, twelve and fourteen.
In one of the Geronimo Stilton books, a door is slammed on Geronimo, and he describes himself as peeling off the door, flat.
In the Stephen King novella "The Library Policemen", the main character attempts to invoke this in a commissioned poster for roadside safety, intended to be displayed in a library (and thus, theoretically intended for children). However, his client rejects the cartoony "kid + steamroller = cardboard standee of kid" design in favor of a more realistic "kid + steamroller = horrible red jam smeared down the road" design.
On Whose Line Is It Anyway?, one session of Party Quirks involves Wayne Brady as "assorted celebrities being run over by a steamroller", sans cartoon effects of course. At one point he impersonates Gary Coleman, and gets squashed flat much quicker.
In the 1960s Batman TV series, a villain uses a weapon that turns Batman, Robin, and Batgirl into...well, Flatman, Ribbon, and Flatgirl.
Also happens to Beautiful Day Monster, in a sketch where Paul Williams is a travel agent. After BDM asks for progressively cheaper travel accommodations, Williams drops a giant weight on him to mail his squished form.
In the "Lil' Bat" segment of The Aquabats! Super Show! episode Eagleclaw!, a ghost squishes Lil' Bat into a pancake shape when hitting him with a mallet.
In an early strip of U.S. Acres, Orson's brothers do this to him when they "play squash".
This happens to Garfield in one Sunday comic after he picked a fight with a larger cat. Jim Davis said he drew a rough sketch of Odie carrying home a flattened Garfield and though it was so funny, he had to find a way to use it in an actual comic.
In Yoshi's Island, there are 3D walls that can fall down on Yoshi. When the walls rise back up, Yoshi peels off in a paper-like state (which was very impressive for SNES standards). Later on in the game, Baby Bowser defeats Kamek by stomping on him repeatedly, then Kamek falls down, flat.
In Mario Kart there have always been ways for racers to squash their opponents flat for a limited amount of time, making them go slower. In the earlier games, you could shrink them with lightning and then squash them, and in Mario Kart Wii, there was an item that allowed your own kart to grow, which would allow you to squash any opposing karts that you would run into.
This is one of the standard Amusing Injuries for the Mummy in Sphinx And The Cursed Mummy. It allows him to fit through bars and tiny gaps.
The Sega All-Stars Racing games do this in a wide variety of ways: By Billy Hatcher's special move and Amy's special move◊, rolling objects or steamrollers (in the sequel), landing on another racer, etc. It is always accompanied by a cartoonish *SPLORT* sound.
When Jigglypuff is defeated in the 3D Pokémon games, it deflates and flattens out.
Introduced in the 5th generation, the Bug-type move Steamroller flattens the opponent Pokémon's sprite while a big roller squashes it flat.
Some of the deaths in the Sierra games have you end up squashed flat.
Happens to the player in the game "Zombies Ate My Neighbors".
Happens to the enemies (Or your party) in Chrono Cross when the summon Golem is cast.
Happens in one death scene in Brain Dead 13 when the giant Living Statue squashes Lance with its big hand and spreads his... paint mess... on its body. This will also happen if Lance doesn't dodge Moose's shoulder charge.
In Sonic Riders, players can get flattened. They will lose their board as they do so, however (but it reappears when they become 3D again).
Some characters in Sonic Fighters have attacks that will flatten the opponent's head. And it's hilarious. You can even get smushed down to a small size (and on the XBLA/PSN versions, you get an achievement/trophy for doing so).
In Sonic Generations, if Classic Sonic gets caught between the truck and a wall in City Escape, this will happen to him.
In the first game Crash gets flattened if he gets hit by a stone wheel in "Jungle Rollers" and "Rolling Stones", by a boulder in "Boulders" and "Boulder Dash", or the barrels in "Toxic Waste". In the case of the wheels and barrels, he pulls himself up for a few seconds then falls back down.
In the third game Crash can get crushed by the stone blocks dropped by some of the Mooks in the Egyptian levels. If he doesn't have an Aku Aku on him he'll walk around with his feet under his head but if he does he'll spring back into shape. He can also get crushed by the triceratops in the prehistoric levels, and flattened vertically by the walls in the Egyptian levels.
In Rayman Origins and Rayman Legends, Rayman will squish when he is slammed into a wall, or slam-jumped on by co-op players. Also, Globox can use his body fat to compress himself when he wants to duck or crawl.
Can happen in Sim Farm if the animals encounter cars. The animals are fine, they just look like pancakes (or bloated, as the game is played from a bird's eye view.)
The titular superhero team of The Wonderful 101 can get flattened if enemies land on or drive over them. To avoid this, they must use the "Unite Guts" ability, which will transform them into gelatin and stun the enemy instead.
In Pac Man Party, there is a minigame that involves avoiding giant wood blocks. If you get squished, this trope occurs and the character floats off.
The Fairly Oddparents uses this trope some. One prime example is the episode "Freaks and Greeks" in which Timmy is trying to protect his mother's glass case from the gods of Mt. Olympus who use his living room as a place to party. "Don't ask." When the case is about to fall Timmy runs to it and tries to stop it from falling. It falls on him and when the case is removed Timmy is on the floor; very, very flat with a stunned expression.
The Looney Tunes should get a special mention because of all the variations they would put on this trope. Sometimes characters would turn into puddles of goop with mouths, sometimes they would spring back up after being squashed into an accordion shape, or they might bend in certain ways depending on what hit them. They really had to mix it up, though, because some character getting hit with an Anvil On Head was pretty much a requirement for every other short.
Happens to Applejack in the My Little Pony: Friendship Is Magic episode "Applebuck Season". She ends up face-planting several times while trying to jump off a tower and onto the other end of Rainbow Dash's catapult while severely exhausted, but she only flattens out the first time.
Happens twice in "Feeling Pinkie Keen" to Twilight Sparkle with a door. (Sort of. Once she peels herself off, she retains her shape with no inflation, as if her body only went into the door.)
In "Luna Eclipsed", Fluttershy pancakes herself on the door of her house when Twilight closes it all of a sudden.
Special mention goes to when Eddy is trying to get rid of Ed's loose tooth by painting a jawbreaker on a fence knowing that Ed would think it's real and run face-first into it. He does so while Double D is in the way, flattening the latter into a circle and him commenting "I've been violated."
Some episodes of The Grim Adventures of Billy & Mandy feature this, but the best example being in the Big Boogey Adventure, when the ship that the villains are on gets flattened vertically, and then falls over on its side.
Buttercup becomes this in the The Powerpuff Girls episode "Down n' Dirty", and Bubbles and Buttercup are squished together in the episode "Mask Scara".
Parodied in an episode of ˇMucha Lucha! where Rikochet's rambunctious twin uncles appear to flatten him and his mother, then they come on screen and the latter complains that they stomped over their cardboard cutouts with Rikochet adding that they can only get them in Tijuana.
Teen Titans Go! has this happen to Robin after getting body slammed by Mammoth in "Gorilla". Starfire and Raven also do it by themselves while Robin is shouting at them at the end of the episode. For some reason.
Happens all the time in Earthworm Jim when Jim, his enemies and others have heavy objects fall on them.
In one of the comedy-focused episodes of Sonic Sat AM, Sonic and Rotor knock down a door that Antoine was standing behind. As they leave, the door goes back up, and we find that Antoine got flattened.
Can happen in a paper or steel mill. The paper machines and rolling mills can crush a man in a second.