to view testicles from behind usually caught on camera upon showing your friends your arse and leaning a little too far forward
On reviweing holiday pics:
"that was when you got your arse out, whats that dark patch between your legs?"
The part of a man no one should ever have to see. More specifically, the back of a man's scrotum.
Dude, when I was in the locker room today I totally saw some old guy's wrinkly backsack.