My 14-year old cousin openly stares at herself and POSES in mirrors and windows when we're out. I want to strangle her every time she does it. Her Facebook pics are all of her friends and herself posing like they're Gisele Bundchen. Gracious! Kids these days...
I hate to break it to you, but she would have lost her virginity by now. Classic behaviour to suit that comment.
Try talking to her.