The sexual position in which one of the participants "The Giver" preforms analinguis or a "Rim-Job" on the other partner "The Reciever". This can include but is not limited to the penetration of the anus with the tounge and even the consumption of some amount of fecal matter.
Mike: Yo man did you hear about Marie and Troy?
Ryan: That weird nerdy couple? No what happened?
Mike: Troy finally convinced her to let him go down on her, and she freaked out because he gave her ass-to-mouth! Isn't that sick?