The act of not wearing underwear, for females. Just as mud flaps behind the wheels of a truck flail wildly in the wind, a saggy vagina may mimic this flapping motion without the restriction of underwear. This is the alternative to "free balling" meant for female use only.
by PACHFI May 05, 2010
Friend #1: I was have amazing anal sex with that filthy little filly Stacy and I pulled it out and put it deep in her bum, straight mud-flappin' bro.
Friend #2: Amazing, pure class.
Friend #2: Amazing, pure class.
by Timothy0Peden September 16, 2021