Two little words, but pack a big punch. More folks are using it instead of saying “get out” when they don’t believe something you said, or “really” or “you don’t say”! So here’s the problem, someone who doesn’t speak so good english overhears you tell someone “shut up” and that person keeps talking, they are confused!!!! Someone tells you to shut up and you do, so they keep talking to you and can’t understand why you don’t answer. They are confused also. So there you have, in the land of I’m confused and so are you!