The act of performing analingus on another person. eatin butt can apply to heterosexual or homosexual analingus; it can be guy on guy, guy on girl, girl on guy, girl on girl. In gay sex, eatin butt is more extreme than rimming; rimming involves merely licking around the anus with no insertion of the tongue, while eatin butt involves full penetration of the anus with tongue. Usually eatin butt is done to lube and loosen up an asshole prior to fucking it.
Ron dumped his boyfriend cuz the guy farted while he was eatin butt, and he got a tongue fulla scat.