The action of slapping your junk/balls against your thighs to produce a sound.
Roommate 1: Dude, what the hell was that noise from your room last night!?
Roommate 2: Just me standing in front of the mirror slappin' out that flappywappins.
Nickname given to bales of marijuana thrown overboard or out of airplanes. Origin is reportedly from members of the US Coast Guard in the area of Southern Florida.