1) Dress as your favourite cocktail or entrée,
2) Come dressed as the lovechild of your favourite two communist dictators,
3) Russian Penguin party - byo ice cubes (can be merged with theme two if you are feeling particularly esoteric),
4) Kermit the Frog party,
5) Evil Villain party,
5) Schoolgirl and Garry Glitter party,
6) Come dressed in formal gear if you run out of time :)
Keeping in mind this will be outdoors, and probably about 10ºC (around 50ºF).
I was toying with the idea of making a large paper mache penis, and wearing it as a tail (because then it'd be a cock tail..haha). The party is on Saturday, so I still have a few days to decide and find an outfit.