When your mother in law walks in and catches your balls in the air slapping her daughters taint .
Or when you are pounding that ass and your balls are slapping against the taint
I walked in and caught my brother and his girlfriend slapping taint.
When a man lifts up one leg and usually places his foot on a desk or bench to maximize the amount of air that flows past his balls; hence ball draft !
That's a helluva ball draft that he's using to air-dry!!