An imperative to be quiet or cease talking immediately. Can be rude, aggressive, or jocular depending on the context. Shut your gob, 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 gob! 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 gob, Dave. I think it looks just fine."