Stand in Portrait

"Who puts a picture frame on a window?!"

—Candace, Phineas and Ferb

When you don't have time to cut out the eyes in a painting for a Portrait Painting Peephole, the next best thing to do is strike a pose and imitate a painting or picture so as to spy on your friends.

When you get right down to it, this is a trope that really requires only two dimensions in order to work, as anyone with a functioning brain could probably determine the difference between a highly realistic painting, and someone sitting in a room behind the wall because of depth perception.

Examples of Stand in Portrait include:

Art

There's an inversion in a couple of Rene Magritte paintings, where the painting within a painting depicts a scene precisely matching what's behind it (right down to the positions of clouds, which shouldn't match because they move). But hey... it's really just one painting, get it?
A recent minor trend in artwork subverts this; it turns out that if you apply makeup carefully to a person and make them sit very still, it's actually difficult to tell they aren't a painting if your angle on the person isn't changing.

Anime & Manga

Yoh does this in Crying Freeman. In this case, he was actually standing in for a painting of himself, and it was on an easel, not a wall, so he just switched in an empty frame and stood behind it with the lights off. He only does it to fool police watching from outside, and once an actual person entered the room, she quickly noticed something was off and turned the lights on.

Comics

One Josie and the Pussy Cats story had this. The Pussycats visit an art museum. they take a moment to comment on a portrait of what Melody calls 'an ugly guy'. After they leave, it is revealed that the 'portrait' is actually a real man standing behind an empty frame, who is unamused.

Film

The Three Stooges short "The Hot Scots", Justified in a 3D medium as the stooges are imbeciles.
- Occasionally subverted in that we're left to assume the actual painting has come to life. The ghostly Shemp causing a portrait of a cowboy to shoot in "Heavenly Daze"; Curly being left to shake a sculpture's hand in "You Nazty Spy"; and a portrait of Napoleon catching the stooges' turkey and running away in "I'll Never Heil Again."
Indiana Jones and the Temple of Doom, a Thuggee in the shadows pretends to be part of the mural in Indy's room before attacking him.
In Like Flint: Derek Flint dresses up as a Z.O.W.I.E. officer and stands in front of a recruiting poster before infiltrating a Top Secret Z.O.W.I.E. complex.
In WALL-E, the captain lures AUTO out by standing in front of a hologram of the plant, pretending that he has it. Then, he hides from AUTO (momentarily) by standing in front of his own portrait. This is slightly more realistic than most, since AUTO only has one ~~eye~~ camera, and so has no depth perception
In From Russia with Love some of the scenes featuring Rosa Klebb had to be reshot after the set was struck. The solution was to blow up a still frame from the existing footage and film the reshoot with the actress standing in front of her own image.
Envy stands in front of her own poster at the coffee bar in Scott Pilgrim.
In Jurassic Park III, a raptor stands behind a glass tube to pretend he's one of the dead test subjects.

Literature

Variation in Gene Wolfe's Book of the New Sun novels: Severian is surprised to discover that what appears to be a painting in a gallery is in fact a cleverly disguised room behind a picture frame.
In the children's book Flat Stanley, Stanley foils an art museum robbery by pretending to be a painting. Of course it's easier for him, what with being flat and all . . .

Live Action TV

When The Monkees played a creepy house, the owner [a vampire] did this.
Spoofed in the Scrubs episode My Jiggly Ball when Kelso tries to hide as a himself in a mural. He refuses to break cover even when Cox points out he is 3 dimensional and then physically grabs him.
In Get Smart, Agent 13, who is hiding in a picture, complains that he cannot look around that much. This is especially goes for leaning out for a look, as he complains "I'm not a pop-out painting!"
Wizards of Waverly Place episode 21 where the Mona Lisa made to come alive does this.
Fozzy Bear and Avery Schreiber did a sketch based on this in one episode of The Muppet Show.
In an episode of The IT Crowd, Moss and Roy do this, not to a hide a person behind a picture frame, but to hide a fire behind a monitor frame.

"Nice screen saver!"

Video Games

The Curse of Monkey Island has a puzzle based on this trope: In order to convince a local innkeeper that he's a member of the Goodsoup family, Guybrush has to take a painting of one of the Goodsoups, cut out the face, paste the remains of the painting on a door with a porthole, and peek his head in through the other side of the porthole as the innkeeper arrives to admire his paintings. Lampshaded subtly in that the innkeeper says he feels as if the painting's eyes are following him, Ã la the Mona Lisa.

Web Original

This has been used in several Creepypasta.

Western Animation

Phineas and Ferb: The opening theme features Phineas painting a mustache on Candace's portrait, but it turns out to be Candace herself.
- In the episode "Fireside Girls Jamboree", Candace makes a snarky comment about the portrait of Elisa M. Fireside, but Ms. Fireside gets out and berates her. Candace even gets the opportunity to lampshade the trope.
The Simpsons: In the episode "Double, Double Boy in Trouble", Bart comments on a poster of Joe Montana, but it turns out to be Joe Montana standing in a hole in the wall.
- In "Monty Can't Buy Me Love", Lisa watches DVD Commentary for The Postman, with Kevin Costner narrating using a split-screen. It turns out he's actually inside the television, and steps out to talk to her.
Kim Possible: In the episode "Graduation", Ron comments on an ugly portrait in Killigan's castle, only to find out the portrait really is Killigan.
Daffy Duck/Porky Pig short Daffy Doodles: Daffy is the "Mustache Fiend", who goes around drawing mustaches on pictures. Porky Pig is a cop who tries to catch him by holding up a picture frame in front of his face and pretending to be a picture. Watch it here, starting at 1:50.
In the Bugs Bunny short The Hair-Raising Hare, the orange monster (now known as Gossamer) does the Portrait Painting Peephole bit, but Bugs catches on and gives him a poke in the eye. Then Bugs stands in for a portrait, which gives the monster a chance to get even... only Bugs beats him to the punch and pokes him again.

Real Life

In an inversion, the Soviet Union edited the disgraced Leon Trotsky out of old propaganda films by back-projecting and re-photographing the scenes where he appeared with a non-lookalike actor standing in front of his image to block it out.