The fact that something like this exists really shouldn't surprise me this much, but it's still disgusting. And really, the app itself isn't a horrible thing by any means. But, if this was around when I was in High-School I doubt I would have had a good time. I'm not sure there's much you can do really, there isn't any way to ban it as a service, nor do I think that's the best course of action.

The internet can be a truly scary thing, people aren't afraid to say really hurtful things and lies when they're anonymous. IMO, the Principal's suggestion of not looking at it, while a decent suggestion, doesn't make tons of difference when you're walking through the halls and everybody's staring at you and their phone and quietly laughing.