peckerboo
The most unpleasant situation where a man's penis unexpectedly maneuvers its way out of the fly hole of his underwear. A peckerboo usually occurs as the result of either (a) a sudden movement or (b) walking for extended periods. Public Peckerboos are the most severe, as they force a man to adjust his junk in front of everyone in the room.
Man I'm sorry I just grabbed my junk in front of your mom, my di#k was playing peckerboo.