When you go to the bathroom and your feces comes out looking like watered-down split pea with ham soup. Pure liquified feces. The foul stench engulfs the entire bathroom. Lysol disinfectant spray is used to combat the stench; however, a "ghost trap" (from the movie Ghostbusters) would be more suitable since the stench is a presence of its own. Mud Demons usually are created when the unsuspecting individual drinks a pot of coffee, smokes a pack of cigarettes, the morning after a hard night of drinking, and/or when eating cereal containing high amounts of fiber (i.e. LIFE, Frosted Mini Wheats, etc). See also Explosive Dirrhea.
Bring a roll of toilet paper and a cross!!
Stan: Dude, what the hell did you do to this bathroom?
Jay: Sorry dude but I had to perform an exorcism on a mud demon.
Stan: You were exorcising a mud demon?!? I can't even breathe!
Jay: It's soul may still not be at rest. Turn on the fan and I'll find the Lysol.