The leaky excretions that are a byproduct of diarrhea. Also is used to reference the Cleveland Browns and can be used as a battle cry whenever the Browns score.
"Last night my friend had a steak and cheese and then exploded brown sauce all over the bathroom."
Friend 1: "What's the score of the game?"
Friend 2: "24-7, Cleveland's killing New England."
Friend 1: "BROWN SAUCE!!!!!!"