Skeleton Key Card

In TV land, some 90% of locked doors can be opened in seconds by following three simple steps:
 * 1) Insert a credit card between the door and the frame just above the lock.
 * 2) Jiggle card a bit.
 * 3) Turn handle.

Up to a point, this used to be Truth in Television. Early spring-bolt locks could be circumvented with flexible strips in a similar way (though actual credit-cards are usually too stiff for the purpose), especially if carelessly installed. However, lock manufacturers introduced features to prevent this kind of attack a long time ago, and dead-bolt locks were always immune to it.

Not to be confused with a Skeleton Key. Or The Skeleton Key.

Advertising

 * Given that Barclays Bank used the advertising slogan "a Barclaycard gets you anywhere" and had several ads featuring a James Bond parody, so it's an odds-on bet this trope came up at least once. This slogan is also responsible for the SAS nicknaming their door-breaching shotguns "the Barclaycard".
 * A 118 118 advert has somebody trying this and failing, only to be handed a fake moustache which opens the door no problem.

Film

 * Subverted in Get Smart. Agent 99 points out that the credit card won't open the deadbolt lock that 86 is using his card to open... until Max reveals that the secret heat laser built in will certainly do the trick.
 * Lenard uses this tactic in Memento.
 * Parodied in The Naked Gun where Frank tries this with Brand X card and it doesn't work. He tries it with an American Express card and the door opens.
 * The French Connection. Popeye Doyle's partner uses a credit card to get into Popeye's apartment.
 * Parodied in the James Bond film A View to a Kill, where Bond pulls out a credit card to unlock a window. But after flipping it over we see that it's an electronic lockpick from The Sharper Image.
 * Superman IV: The Quest For Peace : Lois uses a credit card to get into Clark's apartment to return the cape he lost in his battle with the Nuclear Man.
 * Ace Ventura did it with a door sign.
 * Subverted in Roxanne. Charlie is called to Roxanne's house to unlock her door. He opens his tool chest to reveal nothing but a single credit card, however the door doesn't take Master Card. He then uses the Old Reliable method to gain access to her house (deftly scaling the 3 story home to crawl in through the unlocked attic window).
 * Fletch plays with this one when the titular character, trying to avoid his ex-wife's attorney, uses a credit card on a window to break into his own apartment.

Literature
""You see, the lock on the back door there's a Yale, and with a Yale the bevel's always facing you when you're on the outside. So if you take a credit card and slip it in, you'll find it's just strong enough and just flexible enough to—" "I know, sir. I've seen it done on the telly." "Oh." "And the lock on the back door there isn't a Yale, is it? Goodnight, sir.""
 * A few characters do a similar trick with a knife at various points in the Catteni books; the protagonist explicitly compares it to the credit card trick.
 * In Odd Thomas by Dean Koontz, the title character jimmies the lock on a sliding glass door using an ID card. Although, IIRC, this was stated to have something to do with the general disrepair of the home... or, at least, a fairly valid explanation was provided.
 * It's mentioned in some of the Philip Marlowe stories by Raymond Chandler that Marlowe carries a strip of celluloid in his wallet precisely for this purpose (this was in the days before credit cards).
 * In The Seventies, National Lampoon published a parody called "The Big Recall", starring Ralph Nader as a detective. The sole reason he kept a gasoline credit card was to break into buildings; he figured that the interest rates the corp. charged justified his using its card that way.
 * In the Inspector Morse book "The Dead of Jericho", Morse (who has no official standing in the case) makes a surreptitious investigation of the crime scene, and is caught by Detective Constable Walters. Once Morse has satisfied him about his motives for being there, Walters asks him how he got in. Unwilling to reveal the real answer (which involves bribery) Morse attempts to use this trope as an explanation:

Live-Action TV
"MacGyver: Gee, I always wondered who invented that..."
 * In the Seven Days episode "Pinball Wizard", Parker uses his newly acquired "Platinum Card" first to rent a Porsche and then to break in to a girl's apartment.
 * Subverted in Friends, where Chandler tries this to open a locked cupboard, but loses his credit card through the gap.
 * I remember House pulling out a credit card and betting his minions he can get into a house in 20 seconds, but pulls the key out from under the mat after they confidently take the bet.
 * When master improvisator MacGyver travelled (hallucinogenetically) into the past, he witnessed none other than Merlin himself pulling this stunt.


 * Subverted in I Dream, where a pair of characters destroy every (fake) credit card they have trying to open a door this way.
 * Home Improvement has an episode where Tim, attempting to show the efficacy of the anti-theft system he's installed, has a guest star thief try to break in. Moments after saying that he's engaged the system, the front door opens and the thief walks in. He explains that he used a credit card to slip the lock. Tim replies "Sure, if you don't mind destroying your credit card doing it" to which the thief says, "That's why I used yours" and hands Tim's wallet to him.
 * Subverted on Perfect Strangers when Larry tries to open a door with his credit card and it breaks.
 * If you're Dean Winchester or Lt. Templeton Peck, you just Averted Trope this and use a paperclip, which is just about as realistic.
 * Although Dean did use a credit card to get into Angela's house in "Children shouldn't play with dead things". Of course, when Angela's roommate freaked out at his being there he calmed her down by showing her he had a key, so... maybe he was just using the credit card as a joke?

Video Games

 * Lampshaded in The Curse of Monkey Island.
 * Nethack lets you use your anachronistic credit card to open any lock - even, for some reason, padlocked treasure chests.
 * Maya Fey did this to escape her captor in the fourth case in the second Phoenix Wright game. She managed to open the door, but she was still caught.

Western Animation

 * Deedee does it in the very first episode of Dexter's Laboratory.
 * In the Looney Tunes short "Box Office Bunny", Daffy Duck, outraged at the prices of movie tickets, pulls out his library card - and uses it to open the back door of the theater.
 * When Goofy tries this in a Mickey Mouse Works short, he only gets a sales receipt for the door.
 * Viper invokes this trope in Jackie Chan Adventures when the entire gang is locked up in Section 13. However, Jade pulls out a macguffin "card" that renders this trope meaningless.