I'm worried about my promiscuous friend?

I'm 13, and my friend Angela is a little...out there. She flirts with a lot of guys, and she even gave them a lap dance in gym cl once. She wears thongs, and sometimes no underwear. I even heard a strange rumor about her giving a guy a ******* in the bathroom. I also heard that she sends ual text messages to her boyfriends. For example, she'd say that she wants to get in the shower with them and do it. She's 12. What should I do?