The popular
slang term "put a sock in it" is a request for someone (the person being told to
put footwear into their body, specifically their
mouth) to be quiet.
According to many sources, the phrase derives from the olden days of radio and song recording. Back then, one of the only ways to turn down the volume on instruments such as horns and trumpets was to literally stuff a sock into them. This makes them considerably quieter, and therefore this pratice is the basis of the saying "to put a sock in it".