Impossibly Compact Folding

"Barnacle Boy: Drive? What do you know about driving the Invisible Boatmobile? Spongebob: Tons. Like the windshield wipers are right here. (pushes a button) Barnacle Boy: Don't touch that button, that's the... (folds into origami swan) ... Origami Button."

- SpongeBob SquarePants

In some works, a character will pull out a small piece of paper or metal, which will then unfold to an object many times its original size. In others, a large object will fold itself up into a smaller one. Either way, the object becomes much smaller than is at all reasonable (and may also change mass accordingly) through folding.

A subtrope of Hammerspace and Toon Physics, and a supertrope of Telescoping Robot. May overlap with Transforming Mecha, Bag of Holding, Swiss Army Weapon. or Retractable Weapon.

Advertising

 * A commercial for the Syfy featured a car folding into a briefcase. May be a Shout-Out to The Jetsons (see Western Animation entry below).

Comic Books

 * The Flash's entire costume is stored inside his ring.
 * Iznogoud features an example of this. In "Iznogoud's Nightmarish Birthday", he opens a very small box and extracts a small piece of paper and proceeds to unfold it (it's so small that he needs a magnifying glass to start to unfold it). When completely unfold, the paper is several metres large. Of course, the box had been given to him by the guild of mages...
 * At one point in the original comic-book version of The Tick, the Tick and Arthur take a road trip; the Tick insists that he knows how to fold up their (standard US-style) road map, but every time he tries, he produces an even larger wad of paper, until he's filled up the entire backseat of the car with it.

Film

 * In Sorcerer's Apprentice, when Dalthazar gives Dave the book, Dave unfolds it from tinyness.
 * In Transformers, the allspark cube-thing goes from the size of a house to the size of a basketball.
 * In The Simpsons Movie, Homer has a small billboard-sized poster of Alaska folded up to the size of a business card.

Literature
"Rufo's baggage turned out to be a little black box about the size and shape of a portable typewriter. He opened it. And opened it again. And kept on opening it and kept right on unfolding its sides and letting them down until the durn thing was the size of a small moving van and even more packed."
 * One Norse god can fold up a ship and stick it into his pocket.
 * Robert Heinlein's Glory Road. The foldbox which carries all of the team's equipment.


 * In Robert Heinlein's short story "And He Built a Crooked House", a mad architect designs a house in the form of an unfolded tesseract (four-dimensional cube); it is constructed in Southern California; an earthquake causes it to fold up. Into the fourth dimension.
 * Planetron, star of two children's books about the solar system and the galaxy, unfolds from the size of a toy robot to a fully functional spaceship, and back.

Tabletop Games

 * Paranoia adventure The Yellow Clearance Black Box Blues, Mission 4. In order to enter Troubleshooter Headquarters the PCs must enter a huge machine. If they do so (or if they refuse to do so), the machine folds in on itself repeatedly until it's the size of a suitcase.
 * Dungeons and Dragons module I12 "Egg of the Phoenix". The title egg is an homage to the foldbox in the Glory Road entry in the Literature section. It can be opened up multiple times, each time becoming larger.
 * There is also a folding boat.

Video Games

 * The Pokémon games feature a bike that can be folded up small enough to fit into a backpack, although this may just be an example of Bag of Holding.
 * Manny Calavera of Grim Fandango can fold up his huge Sinister Scythe to fit in his coat pocket.

Western Animation

 * George Jetson's car could fold up into a briefcase, which he can easily carry into his workplace in the show's intro.
 * Phineas and Ferb loves using this.
 * As seen in the page image, Ferb once unfolded a map from a roughly two by two inch square into a world map larger than the house it was leaning on.
 * Their "Plataposterior" robot is about 10 feet tall, but folds up into a square that fits in Ferb's front shirt pocket.
 * The full-sized chemistry lab they carry around with them also qualifies.
 * Also the "Wrapped up in a nice little boxinator" literally compacts his WHOLE BUILDING into a tiny box.
 * A common gag on Looney Tunes is for a character to fold a large box, door or what have you, into a square the size of a matchbox.
 * SpongeBob SquarePants: Pushing the origami button on Mermaid Man's invisible boatmobile folds it and everyone inside into a paper crane.
 * In an episode of The Simpsons, Homer folds a Giant Novelty Check into a small wad and stuffs it into his pocket. Then it expands.
 * On one Pink Panther cartoon, Pink is hungry, so he folds up the background to the size of an index card, sprinkles salt on it and eats it. It then unfolds inside him.
 * Lampshaded with the credits of Rocky and Bullwinkle, which Bullwinkle claims "are all here on this itty-bitty card"; the card then folds out to list the cast and crew.
 * In The Flintstones episode "The Hit Song Writers", the celebrity songwriter Hoagy performs Fred and Barney's song on piano, then immediately folds the piano into a briefcase and exits the stage.
 * On How to Hook Up Your Home Theater, Goofy opens the "easy" instrctions for the home theater. Unfolded, they cover most of the room.

Real Life

 * The current world record for folding a piece of paper in half is 12 times. That's about 4,096 layers (2^12).