I think it would be better to just do your best to not put yourself in a situation to get raped. Heck, part of my reasoning behind getting a big dog was so I could go out running in the evening and worry less about drunk creepers in a college town.
I mean, sometimes stuff happens that you can't avoid, but a lot of times girls will put themselves in the situation. Like walking around alone at night, or going home with a strange guy after getting drunk, etc. If the girl thinks that she should probably wear one of these anti rape condoms to go do something, then she probably shouldnt be going in the first place.