You Guys Rock
U boys have expressed ROCK !! ??
Basically it means you are great! U is dumb because your letters sound like your words. Another way to say cool or cool is rock.
Swing rocks are usually used only by teenagers and the like, but many young people use them. You hear it more often when you talk about music.
Another term you may hear is that you are sick! Or he's sick! In this context, bad meaning is very good. It is more common in English-speaking teens today (at least in North America).
You are the best people