runner's whip

Runner's whip occurs when you are running but your dick be too long so it keeps whipping back and forth until you get bruises on your inner thighs.

Wife: Babe, what happened to your legs?
Me: Oh these bruises?
Wife: Yea
Me: Went for a run last night...
Wife: Oh no, did someone hit you?
Me: Nah bitch, it's runner's whip from my fat long dick!