The gap in your legs when you lift your
leg in
front of you creating the shape of the number 4. Used in the game hackey
sack/footbag.
Playing hackey
sack, a dude goes to hit the bag up with his foot, but misses. The
bag goes in the gap between his legs and crotch.
Dude 1: Aw man it went in my 4
hole.
Dude 2: It always goes in your 4 hole