Wa-Bap Share definition Flag An onomatopoeia exclamation used to demonstrate the swing and blow of a hit. (Usually from the back, as a sort of sneak attack) see shazam I snuck up on Joe with the baseball bat, and WA-BAP! Right to the back of the head! Wa-Bap by Cicatriz December 29, 2004 Get the Wa-Bap mug.