Mud Plunging 

Inserting your penis, dildo, strap-on, fist, ect. inside someone's ass while they are pooping to push the poop back up their ass.

The man put his penis inside the girl's ass right as the poop started to come out, causing the poop to go back in her ass and causing them both to have a not so pleasant feeling but the great feeling of knowing that you accomplished it.

-he is mud plunging her, he mud plunged her, she plunged herself, I mud plunged that filthy whore-

(hint: it would make your life easier for you if you didn't tell people that you mud plunged someone)

Mud Plunging by epg2 November 12, 2011

Mud plugging 

Fucking someone in the ass who has a very shitty asshole and getting shit all over your dick.

Dan's girlfriend had a case of the sloppy shits but he was horny so he gave her a good mud plugging anyway.

Mud plugging by R3P0 August 26, 2006