A term used frequently by the US Army's 82nd Airborne Division. Goo-Butt is a condition that befalls a Soldier who has been in the field, unwashed, in excess of 72 hours. This condition is identified by a viscous, cheesey substance that is secreted from the Soldier's ass and affixes itself to surrounding flesh and clothing. It is composed of sweat, bacteria, dead skin cells and fecal remnants.
Man, everytime I drop trou to take a dump in the field I get smacked by an angry cloud of goo-butt!