Photobomb means to drop in a photo unexpectedly or to hop in a picture right before it is taken.（照片炸彈指意外被拍進照片里或者在照片拍攝的一瞬間進入鏡頭範圍的行為。）

It can also refer to an otherwise normal photo that has been ruined or spoiled by someone who was not supposed to be in the photograph. （另外，照片炸彈也可以指本來正常拍攝的一張照片因為不相干人的出現而使照片失去原有的意義。）

The most common photobomb is someone in the background making a face. （最常見的照片炸彈就是有人在照片背景裡做鬼臉。）