Photobailing
Intentionally leaving or "bailing" a planned photo at the last second, much to the surprise of the others in the photo as well as the photographer. If you photobail, you play a practical joke by disappearing suddenly from a group photo without letting others know of your plan to leave.
While her friend with the camera shouted "1-2-3", Jane left a gaping hole in the group picture by photobailing just as everyone else yelled "cheese".