Went as the invisible man this year. Wore a suit so you couldn't see the big empty hole in my chest where my heart was cut out. Ok, I am invisible, so it wouldn't matter if I didn't wear the suit because you wouldn't be able to see a thing anyway.
Truth is that the effect is much more pronounced this way than if I chose not to wear clothes at all. There is something discombobulating about the hat and clothes seemingly floating by themselves.