keep one's mouth shut

keep one's mouth shut  {v. phr.},  {informal}
To be or stay silent. — A rude expression when used as a command.
When the crooks were captured by the police, their leader warned them to keep their mouths shut.
Charles began to tell Barry how to kick the ball, and Barry said angrily, "Keep your mouth shut!"
Syn.: SHUT UP (1).
Categories: informal rude verb