1. A tendency to speak brashly or inappropriately. TImmy's got a bit of a mouth on him, so he's always getting into trouble at school.
2. A criminal lawyer. If your mouth isn't there, they'll definitely try to get incriminating information out of you.
1. n. a hangover. I’ve got quite a mouth this morning. I guess I overdid it.
2. Go to mouth(piece).
See also: mouth