A moonbomb is essentially a photobomb in which the photobomber removes his pants and directs his bare bottom towards the camera. This results in a photobomber mooning the camera thus creating a moonbomb.
In the background of our picture, you can see Jack photobombing, but he couldn't just do it normally. Instead he had to moonbomb the camera with his hairy ass.
by PhotobombExpert October 31, 2012