Piss chaps is a phenomenon that happens to some individuals when they have been consuming copious amounts of alcohol. After an individual has drank excessively, they may have the unfortunate instance to wet themselves, sometimes through no fault of their own. The area of their pants that is wet versus the area that is dry resembles that of an individual that is wearing chaps. The person donning the piss chaps may or may not be conscious.
Man 1: What the hell happened to you?
Man 2: I passed out at the bar.
Man 1: Looks like you had an accident in your pants.
Man 2: How can you tell??
Man 1: You're wearing your piss chaps!!!