Mud-flapping 

the process of getting shit on your shirt while wiping your ass

I had to change my shirt because my last one got caught in a mud-flapping accident.

Mud-flapping by myrtle1994 April 22, 2020

Mud Flapping 

Turning on the bidet as you begin to defecate, as apposed to afterwards.

Yo! I accidentally turned on the bidet too early. Guess Im going Mud Flapping

Mud Flapping by Gary Inc. December 22, 2020

Mud Flapping 

the act of wiping ones arse in the direction of the moot, hence covering the flaps in poo.

similar to mud bagging (masculine)

friend: hey jenny, whats that smell?

mud flapper: sorry, i just did some heavy mud flapping

friend: mmm, delightful...

Mud Flapping by Dick Champ May 24, 2011

Mud Flapping 

Mud Flapping is when a guy challenges or questions another guy’s manhood based on the former not being capable of a feat that he himself has just proved himself unable to accomplish

Example:

MudFlapper: “Hey bro, you got a knife I could borrow?”
RealMan: “Sorry bro, I don’t have it on me.”
MF: “What?! A real man always carries a knife!”
RM: “YOU don’t have a knife idiot. Stop all your mud flapping and get out off my property.

Mud Flapping by anonymous September 14, 2020

Mud-flappin'

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.

"Dude, it's my laundry day, so I'm mud-flappin' it today."

Mud-flappin' by PACHFI May 6, 2010

Mud-Flappin'

When you are having anal sex with a girl and you pull out and put it into her vagina.

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.

Mud-Flappin' by Timothy0Peden September 16, 2021

mudflapping 

Motorboating (or flapjacking) a girls ass after she poops!

I had to hose down after mudflapping that fat girls ass last night!

mudflapping by jjstl April 27, 2010