To be or stay silent. - A rude expression when used as a command.
Быть молчаливым; хранить молчание. Если используется как команда, то звучит грубостью.
Charles began to tell Barry how to kick the ball, and Barry said angrily, "Keep your mouth shut!"
I tried hard to keep my mouth shut during the boring speech.
Мне с трудом удавалось молчать во время скучной лекции.
When the crooks were captured by the police, their leader warned them to keep their mouths shut.