or you could go with a gimp suit, some whips, and maybe some rope and call yourself a Masochist, Kinky or something to do with Bondage (all three in one. Yay
or put longer ears on and pyjamas, and go as Mr Spock
or a long wig, funny nose mask and go as Michael J.
go as a guy, and say you're a Mr. (or a bloke)
one of those inflatable suits, and say you're Massive.
a green outfit with weird coloured things on it, and pretend to be a Microbe.
get a plastic knife, and be a Killer.
Wear nothing, and say you're a Karma Sutra Practitioner.
Take an inflatable/nerf bat, and be a baseballer.
Find an eligible guy, hang off of him, and say you're a Kimono, or Klothing (Ok,its spelt wrong, but meh).
A rattle and bib, and you could be a Baby.
something uber sexy and you could be a Babe.
power suit and tught bun/ponytail, and you could say you're a Bit(h.