Most Helpful Guy
It is on her. I would have to see it on you to say if it is on you.
That being said, it's better to be original than try to skank it up and do a cliche sexy costume. Any "sexy" costume you can think of has been done a million and one times already by girls who can probably pull it off way better than you can. If you want to get noticed for how you look in your costume, do something original, something that REALLY gets into the spirit of the day. Be scary, be cool, don't skank it up.