keep mouth shut
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keep one's mouth shut (about someone or something)
Fig. to keep quiet about someone or something; to keep a secret about someone or something. They told me to keep my mouth shut about the boss or I'd be in big trouble. I think I'll keep my mouth shut.
keep your mouth shutalso shut your mouth
to say nothing I just keep my mouth shut and do my job, and I only offer an opinion if someone asks me for one. It's important to be a good listener, and that means you shut your mouth and let her talk.
keep your mouth shut(informal)
to keep something secret You can trust Sarah - she knows how to keep her mouth shut. (sometimes + about ) Do you think I should keep my mouth shut about seeing Jim with another woman?