I had my daughter, one year, go as a "no Pest" strip. Get a big box that fits, and cover it with aluminum foil. Glue on a bunch of those little plastic bugs.
One year, a friend and I went as "dirty laundery". We put a clothes-line between us, and pinned up underwear we had gotten at goodwill.
If you get a really big, clear trash bag, fit it up around you, blow up small balloons and stuff it, and go as a "bag of jelly beans".