The unpleasant dilemma arising when one relieves oneself, only to discover that in the process they got a little bit of shit on their hand and thus is reluctant to buckle their belt. Said person will, in most cases, opt to wash his or her hands before touching his or her belt. As a result of the hand washing when they do buckle their belt the moisture left on their hands is transferred to the belt, making it wet.
Dude, I was just leaving a mud monkey
when I got a little bit of shit on my hand so I resorted to wet-belting.