The process of a male shaking his exposed genitals from up and down, in which the penis begins to flap.
Jeff’s Mom: Jeffrey, stop waving your naked penis all over the place!
Jeff: it’s called the guitar flap you dumb bitch!
Jeff: it’s called the guitar flap you dumb bitch!
by Allahman20 August 23, 2021
Get the Guitar Flap mug.