shut your mouth
An imperative to be quiet or cease talking immediately. Can be rude, aggressive, or jocular depending on the context. Shut your mouth, Bobby—no one asked for the opinion of a dork like you! A: "So, where do you think we can sell these stolen goods?" B: "Shut your mouth! Don't you have enough sense not to talk about that in public?" Dave: "Wow, that Cadillac has seen better days. How much did you pay for that little gem?" Bill: "Ah, shut your mouth, Dave. I think it looks just fine."