When one's fake tan is so extreme it looks as if they were rolling in the mud and accumulated inches of mud on their face.

When some little bitchboy is acting like a little tiny pee pee poo poo baby and messing up the group plans.

A mudface is something that only a very sick or filthy woman would let you perform. The quintessential smut peddler's paradise. It involves showering a bitch's mush in shards of gooey shite, preferably with the velocity of a shart. Once applied, the woman leaves it to dry on her face before flaking it off like mud and using it to top a cappuccino.