PhotoZombing 

A subset of Photobombing where someone deliberately appears in the background of other people's photos while adopting a zombie-like pose.

Man did you see James picture on the beach, there's some guy photozombing in the background like totally night of the living dead.

PhotoZombing by Groaning Required September 21, 2011

photobombing 

Intentionally posing in other people's photos, for a later surprise.
Usually people making funny faces in the background, without the knowledge of the main subjects of the photo.

Jim is always photobombing, he messed ups some of the best photos from the wedding.

photobombing by U8IK May 6, 2008

Photobombing 

The act where one or several persons ruin (sometimes improve) a photo by performing funny acts in the background which may include a dry gangbang, holding stick like objects up to your crotch or raising your clothing.

Hey Johnno's been photobombing all the photos from the party. See his ass in the shop window in the background?

Photobombing by ladiesman219 June 23, 2009

selfie photobombing

A picture taken of a random background, often a blank wall, wherein the photographer ruins the photo by inserting their own face. Selfie bombing photos are usually uploaded to facebook, Myspace or any other sort of social networking website.

Also, see selfie and photobombing

Carla is constantly selfie photobombing the photos of her bedroom wall.

selfie photobombing by Chaser33 April 11, 2014