How do you put a bratty, attention seeking, indirectly bitchy teenager in her place?

There is this girl in our community that thinks she is all that. She talks to as many guys as possible because they give her attention (including one of my closest friends). And they continue to fall for it or even get a little hurt by it. I'm in my early twenties, and it's not that i'm jealous at all. People think she is so sweet and innocent though, and now she is starting to talk to my brother a lot (though he can see right htrough her). I've had enough of it. How do you put someone like that in their place?