A man that is willing to have sex with a woman that has IBS (Irritable Bowl Syndrome) or diarrhea. He / possibly she (with a strap-on) has no concern with getting "poop" on their "dick", and will go back for more multiple times.
"Hey Becky, I dont know what to do with Steve. I might have diarrhea."
"If he is a mud dipper, you guys shouldnt have a problem"
The act of sodomizing a woman post vaginal intercourse while she is on her mensus.
My girl made me fuck her on her period, so I finished her with a Crimson Mud-dipper.