Going to a non-formal dance... what do i wear?

I've been to a dance before but it was formal.. this one is non-formal, what do you wear? just jeans and a cute top? or shorts and a cute top? i'm in 9th grade and a girl by the way! :) oh and this is a dance at my best friends school so i don't know any of the guys, not trying to look sl*tty or anything like that, so don't say a really short skirt or something! :) thanks