Abbreviation for "Shut the fuck up no one asked you."
It's used to intensify the fact that you don't want a person's opinion on a certain subject.
Most used when one is irritated or angry.
Sophisticated Aristocrat: I'm terribly sorry, but we must cancel Hannah Montana due to the inappropriate and obscene photos depicting Miley Cyrus.
Befuddled Idiot: No please don't! You shouldn't judge Miley Cyrus because she is a good role model.
Sophisticated Aristocrat: STFUNOAY