When you have your legs up on the table and boastfully fart to your onlookers, and come to the realisation that your booty hole is slightly wet. Take yourself down the toilet to find the yellowest of all mucus in your white underwear.
Hot Yellow Ass Mustard: the result of anally straining oneself beyond one's limits then exposing that matter to a heated element.
After we ate the bean burrito we had a farting contest in which Matt pushed too hard and sprayed ass mustard all over the space heater causing it to become hot yellow ass mustard.
One who pees all over his surrounds. It can be a public toilet, or anywhere else that is public. They usually strike in the bathrooms, either from being drunk or for their urine fetish.