Poop in his mouth 

To poop in one's mouth is a Midwest American colloquial expression, meaning:
1. To poke fun at someone, similar to the English expression "taking the piss";
2. To utterly dominate an opponent, in the context of sports or games.

1. It was first and goal and I was sure Team A was going to score a touchdown, but Team B's defense decided to rush the QB and poop in his mouth, they stopped him no problem.

2. Look at that guy with the mullet over there. I dare you to poop in his mouth.

Poop in his mouth by smerdjik June 1, 2018