I don't know but I can sympathize with her. Please let her know she isn't the first girl who's had to deal with this. When I was a sophomore, some boys spraypainted some really rauchy stuff about another girl and me on the side of a wall. It was humiliating. I mean, honestly, at that point in my life, I didn't even know the meaning of what they wrote. I was a regular kid, cheerleading capt, honor society, no trouble. It was just some mean boys playing teenage pranks. But it really hurt nonetheless.
I don't know what you can do on the net- I'm sure Karen's advice is as good as it gets. but I just wanted to let you know it happens to lots of girls who don't deserve it. So she deserves a big hug and it might make her feel better if her daddy gets all mad (a protective daddy is good for a wounded girls spirit )