The sensation of having a greasy and unwipeable ass usually occuring after consumption of large quantities of fried or fatty foods. A result of oily anal discharge, leakage, or extremely tacky fecal matter. Often accompanied by, or preceded by, 'The Itis.'
I ate two plates of ribs and a half pound of fudge last night. I keep wiping my ass today but I just can't shake this Mud Butt.