goo butt

It's when your ass and taint area get all hot and sweaty after doing strenuous activities such as working out or running, thus resulting in the sweat and stinky goo that builds up in your ass crack and taint.

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.

When your butt has goo coming out of it. Very common