When a man, typically an older man, has quite a saggy scrotum such that when they lay on their back and remove any under panties the scrotum will block the gooch area, thus creating a gooch flap.
Doctor: Time for your prostate exam. Oh my where is your anus?!?! Just kidding I found it, it was hiding right behind your gooch flap!!
by CarlR69 March 18, 2017