A term popularized in a cartoon from the 60's that starred a genius dog named Mr. Peabody. It was his trademeark phrase, often said to the child (whose name was Sherman) whom he would always be explaining history or science to (with his own unusual twist of course). Sherman would retort with a smart remark, to which Mr. Peabody would reply "Quiet, you!".
Sherman: "So you might say, it was a real Pow-wow."
Mr. Peabody: "Quiet, you!"