Photobomb
To pose in the background of a picture being taken
Example
We had one picture where we're all smiling but Jack had to go and photobomb it!

Related Slang
Selfie | A picture a person takes of themself |
pic | Picture |
phobar | Photoshopped beyond all recognition |
pix | Pictures |
awks | Awkward |
An action popular among younger people; commonly involves a nice picture being taken of the subjects but somebody slips in the background with a goofy or creepy facial expression or awkward body pose.