turkey flap

you know how old dudes have that flappy skin underneath their arms? It's kind of like that but between their balls and anus, sometimes hanging quite low (4"-8"). Some guys can even catch waves with it.

Also known as the perineal waddle, taintus gigantus or turkey taint. requisite equipment for any taintboarder

Jon rode Bob's turkey flap before dawn every day they were in Kauai.