Halloween costume ideas for a high school party? please help?

i want a hopefully unique costume for a high school halloween party im going to. it could hopefully be a bit slutty or at least not completely unflattering as the guy i like is going to be there, and i could keep my hair down and my make up not to out there. also if it could use things i might have around the house or could pick up thatd be awesome :) thanks so much i need help alot.