Makeshift HALLOWEEN costume?!?

I have a Halloween dance on Friday and we can't get in without costumes. I need some sort of make-shift costume just for this weekend. I wanted to be a giraffe with a really short giraffe print dress, giraffe ears and a tail.. but i can't find a dress. i can't get out this week though. Any one have any home-made costume ideas!? i have ALOT of formal dresses.