A dry piece of snot that is dangling out of the nostril, usually hanging onto a nose hair. It flaps in and out of the nostril whenever person breathers through their nose.

used as an insult. can be in replace of such words as loser, dickhead or idiot. can also be used as a word for someone who masturbates a lot.

A really fat naked woman who's vagina is flapping every time she moves

Is a pop of the 1920's

a long stringy wet snot from either nostril mostly pinged onto walls

A guy who likes to do pelvis thrust that make his dick flap back and forth.

Flapping is when you fap on a girls breasts and rub your hands on her ass while listening to Ed Sheeran