An unfortunate birth defect whereby one’s digestive tract is reversed, causing one to eat with their ass and crap out of their mouth. The ass must be trained to chew food in the same manner as teeth. A serious side effect of transverse digestion is halitosis.
Derek: “Hey Mike, how come you never eat with us?”
Mike: “I didn’t want you to watch me eat with my transverse digestion condition.”
Derek: “So THAT’S why your breath stinks like shit!”