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.