Birthday Suit Surprise Party

Nakedness. Nobody ever gets tired of it. The exact reasons for being naked are irrelevant, for inevitably the time must come when we must end this plot. Cast aside the foolishness of a naked person traipsing around the universe gay as a chickadee, and finally have them safely at home where the nakedness can bother no one and so-

SURPRISE!

Well, so much for the comfort and all that. Looks like at just the right time, nakedness has become funny again. Because after all, as far as embarrassing humor goes, it's hard to top having all your friends and family see you without any clothes on while celebrating your arrival into this world (amusingly enough, in the same state as you were back then).

Usually the disrobing happens for a deliberate reason. The character in question is under the impression that he or she is about to get some. Oh, you adorable sex hounds! Obviously, this does not show up so much in G-rated versions, which rather involve Naked People Trapped Outside.

This trope is based off an old story, as Snopes explains here and here. The Reveal of the surprise guests almost always ends the story- very rarely does the party happen and then we see what happens next.

Examples of Birthday Suit Surprise Party include:

Advertising

Non-nude variation: A '90s Michelob Light commercial had a woman coming home and finding a note from her husband: "Grab the Michelob Light from the fridge and meet me in the living room." Grinning mischievously, she runs upstairs, changes into a slinky negligee, and comes back down to the living room...
This commercial, which provides the above image.

Film

Subverted in the film In Good Company, where Dennis Quaid's character guesses about the surprise party and comes in in his underwear as a joke.
Although the party's not for him, this still happens to Patrick Dempsey's character in the movie Some Girls.
Happens in the movie Riding The Bullet as the main character is contemplating slitting his wrists.
Perhaps the most classic scene in A Fish Called Wanda, a film packed with classic scenes.
The titular moment of American Pie - even funnier, more explicit and more em-bare-assing in the unrated DVD version.

Live Action TV

Coupling does this. Jeff's Love Interest blindfolds him in the office after hours and says she has a surprise for him. He jumps to the understandable conclusion that she was going to have sex with him right then and there. So, happily singing to himself about how cool it is that she wants him, he triumphantly disrobes down to nothing. At which point the Love Interest returns -- with his parents—and reveals there was a room full of people waiting to surprise him for his birthday party, and they'd been standing there watching the whole strip.
- Oh, Jeffrey.
  - Still, it ends better for Jeff than any other example on this page.
An episode of L.A. Law also does the "in anticipation of sex" version.
There was a sketch on The Benny Hill Show involving a man being invited back to his girlfriend's flat. She leaves to 'slip into something more comfortable'. He strips off in the expectation of sex, then all of his friends leap out shouting, "Surprise!".
Happens to Kenan on Kenan and Kel, although he was not completely naked—just below the waist.
Happens to Jeri Ryan's character in Boston Public. She strips down to just a shirt for some goodbye sex with her ex-boyfriend in the office, only to be surprised by everyone jumping out and shouting "Surpri__ohh."

"OK, you got me."

In the episode War from the La Femme Nikita TV series, assassins break into Nikita's apartment. They thought they'd get the drop on her. They're wrong.

Mythology

One variation on the urban legend: A middle-aged couple go to church on the wife's birthday. After they come home, the wife heads to the bath to take a shower, during which the husband lets in everyone he has invited to the surprise birthday party prepared for her and hides them in the darkened living room. Then the wife comes down the stairs stark naked and enters the living room while calling out to her husband to "come get it while it's clean".

Video Games

Happens in the 2009 Interactive Fiction Competition winner, Violet. Ending spoilers ahoy: The hero is trying to work on his dissertation but is distracted by his itchy clothes. You have to remove the clothes and finish the game naked... when it turns out Violet had thrown you a special "Dissertation finished" party. Subverted in that she knew it was coming, since she rigged your office with a hidden camera, to make sure you keep working.

Western Animation

Happens in the NFB's Bob's Birthday, the animated short on which Bob and Margaret was based. In this case the guests never get to yell "Surprise!"; they just stay in their hiding places and endure the awkward conversation that follows.
Tiny Toon Adventures: Hamton finds himself naked outside after doing something stupid at Plucky's urging (namely, skinny dipping in Montana Max's personal pool). When Hamton finally makes it home, a surprise party is awaiting him and Plucky was aware of it.
- Note that this time, we do see what happens next: Hamton uses a "happy birthday" banner as a loincloth and starts eating the cake.
Foster's Home for Imaginary Friends. "I Only Have Surprise For You" Bloo arranges a surprise party for Mac, just as he got out of the bathtub and all the towels were gone. Bloo does this same prank again, only this time, he provides Mac with a ballerina costume.

Real Life

in Jeffery Brown's autobiographical comic Funny Mishapen Body, while in the hospital as a teenager, a group of well wishing friends from his church decided to surprise him with a visit while partly undressed from his revealing hospital gown and using the portable bedside commode. ... it was awkward.