Super Multi-Purpose Room

Close cousin of To the Batpole, this is a room that has a Transformation Sequence. A mundane living room, bedroom, or small apartment can be converted into a fully-functional Superhero lair by a pressing a simple hidden control button, or pulling down a horribly out-of-place candle sconce.

Named for the room in small schools that serves as a combined cafeteria, gymnasium, and/or auditorium; which is often referred to with a cutesy portmanteau name like "cafetorinasium" or "cafetorium". (Incidentally, the school in the animated show Fillmore had a cafetorium. But that school had everything.)

Many will contain a Wall of Weapons.

A Super-Trope to Feng Schwing.

Advertising

 * A commercial a few years ago illustrated the speed with which businesses must adapt these days, by showing a corner restaurant that alternately transformed into a corner gym and a corner boutique.

Anime and Manga

 * Music Room 3, the base of the Ouran High School Host Club. Platforms rising out of the floor, magically appearing side rooms and musical instruments....
 * Zettai Muteki Raijin-Oh has a classroom that transforms into a giant robot control center.

Film
"Leeloo: Autowash!"
 * In Buster Keaton's "The Scarecrow," two farmhands share a one-room house in which all the furnishings have at least two functions -- there is a record player/stove/oven, refrigerator/bookcase, rolltop desk/sink, bathtub/sofa, and Murphy bed/piano.
 * The title characters' home in the movie Mr. and Mrs. Smith was filled with camouflaged and hidden equipment caches, including a gun drawer hidden as part of a wall oven.
 * K from the second Men in Black movie has a cache of weapons hidden in his old apartment, which is now someone else's home. They have to neuralize this family in order to access it.
 * Even older film example: the gymnasium of Bedford Falls High School memorably transforms into a swimming pool in It's a Wonderful Life.
 * Of course, this was actually a feature of the high school it was filmed in, so Truth in Television as well.
 * In the Bond-movie Tomorrow Never Dies, Chinese female superspy Wai Lin has a run-down bike repair-shop which transforms into a full-blown spy lair.
 * Pick a room in any of the Spy Kids movies.
 * The film Robin and the Seven Hoods, set in the 1920s Prohibition era, features a bar/casino that can transform into a temperance church meeting for when the police show up.
 * Not actually a hideout, but the apartment of Bruce Willis's character in The Fifth Element had a lot of Super Multi-Purpose Room features, simply as a space-saving convenience.

Literature

 * Hogwarts has the "Room of Requirement" which can take on literally any function, to suit the immediate specific needs of the user.

Live Action Television

 * Sarah Jane's attic in The Sarah Jane Adventures, triggered by the sentance "Mr. Smith, I need you." which makes her Magical Computer Mr. Smith awaken and transform the room (or at least the chimney breast).
 * Chimneys have breasts?
 * Only the female ones.
 * In Stingray, the Gerry Anderson series, where X20, the weird sea creature who lives all alone in a house on a rock in the middle of the ocean, disguises the secret sea-creaturey equipment in an ordinary-looking house in case he gets visitors, which he did a few times (though he also had to don a quick human disguise on these occasions as well).
 * Anderson did much the same thing at various times in Thunderbirds. International Rescue's headquarters on Tracy Island is a combination of this trope and To the Batpole, with both huge hidden hangars for the Thunderbirds and parts of the main house -- especially the living room -- that conceal communications devices, radar screens, etc. A more direct use of the trope is seen in the episode "The Impostors", where the stereotypical hillbilly shack of Jeremiah Tuttle, one of IR's agents, has the same sort of comm gear (and who knows what else) hidden in much the same way as X20's house. The Tuttle family pick-up can also go into overdrive and hit high speeds if needed.
 * The Goodies lived and worked in an office that included fold-down beds that were also doors to other rooms, a window showing a choice of vistas or a TV screen, and in one episode, controls that drove the building in the famous Le Mans 24 hours race. Later episodes set in the office included props doing similar versatile work.

Video Games

 * In Deus Ex, when J.C. gets to his brother's room and puts in the code given to him by his brother, the wall opens up to reveal a futuristic computer and enough munitions to, well, easily take care of those pesky M.I.B.s that invade it later on.
 * Starship Titanic has tiny versions of these rooms for guests traveling "Super Galactic Traveler Class" as the furniture folds in and out to create a kitchen, dining area, bedroom, and living area. (Not at the same time, mind.) The problem is that unless you know which furniture plates to unfold in the proper order, the furniture gets in its own way and won't fully unfold.

Western Animation

 * The Hair Bear Bunch had a lot of cool appliances hidden in their phony cave at the Wonderland Zoo.
 * The Tick bugs Arthur to reveal where "the hidden switch" is in the pilot episode. Naturally, there isn't one, and Tick nearly destroys the apartment looking for secret Superhero gear.
 * Spider-Man and His Amazing Friends had one at Aunt May's boarding house, in Queens. Somehow, she didn't notice.
 * In an episode of Pinky and The Brain the bridge of an old harbor-tour boat transforms into a fully-functional anti-sub warfare center.
 * Parodied on Family Guy; Quagmire's bland living room turns into a fully-equipped bachelor pad with the press of a few buttons. In a later episode, there is a chase scene in his house in which every piece of scenery folds out into a bed when knocked.
 * Stewie also has a secret room full of guns ammo and other evil genius type decor.
 * Peter has a hidden base underneath the house where he hides his porn. It was part of a cutaway gag though and hasn't been seen since, so it probably isn't canon.
 * Is anything canon in that show?
 * The 1970s cartoon Drak Pack had one of these, a room in an old run-down haunted mansion that turned into a high-tech communications center at the touch of a Big Red Button.
 * Parodied in The Simpsons - when prohibition is introduced to Springfield, "Moe's Pet Shop" becomes one of these. Barney is sitting on one of the stools as it rotates into the wall - when the room returns to a bar again, his clothes are ragged and he remarks "Those gears down there hurt!".
 * There was another time when some law-enforcing officer enters Moe's tavern for some reason (can't recall why). Upon learning he's facing the law, Moe presses a secret button, which rotates all the tables and walls to reveal roullettes, darts targets and other casino appliances, complete with a croupier. He then remarks "oh, wait, the other one was better".
 * In Cats Don't Dance, Darla's tearoom gains a stage, floodlights and a giant cake, complete with backup singers from nowhere at the pull of a rope.
 * In The Superhero Squad Show, the X-Men's Danger Room is like this, reconfiguring itself to be the gym, the cafeteria, or anything else (while still being just as good at the whole Death Course thing.)
 * The Classic Disney Short Mickey's Trailer has the eponymous trailer, whose interior could transform with the pull of a switch, so that, say, Donald's bedroom could become a bathroom for his morning dip.
 * The Tex Avery cartoon The House of Tomorrow includes a luxurious room that can be made to look like a dilapidated shack in case the IRS man comes to call.
 * In the Looney Tunes short Designs for Leaving, one of the features of Elmer's modern home is a second floor that lowers so you don't have to take the stairs... at the cost of crushing everything downstairs.

Real Life

 * Truth in Television: Emergency Party Button.
 * In some Bavarian homes there is a single wall between the kitchen and the living room. The fireplace built into the wall serves both as a stove and a heater.
 * THIS THING!