A couple years ago this is what I did...
Wear a red ribbon (or cloth, but solid red would do) around your neck, add a flannel shirt, jeans and boots...to give that country flair...and voila...you're a "Redneck girl"...thank you Gretchen Wilson.
And a couple of other ideas that I've used...love those "punny" costumes myself. lol
World's Largest Dust Bunny...wear grey clothes (sweats work great), add one of those large spider webs for decorating with different things you might find behind the sofa...cheerios, money, spiders or other bugs, etc. Wear a pair of bunny ears and a tail. (When I wore this DH dressed in jeans and a t-shirt and carried a broom and dust pan like a janitor.)
DH and did a few "couple punny" costumes...someone mentioned the "Deviled Egg"...easy to do with white sweats and a yellow felt yolk pinned to your belly, add the horns, tail and pitch fork...and you're done. So, I wore that and then DH went as "Deviled Ham". I put him in all pink clothes, a pig snout, horns, tail, and pitch fork...easy peasy.
Another year we did an intellectual couples costume. One of us wore all black with "476 AD - 1100 AD" written on the front. (I used black felt with a silver glitter glue pen to do the writing that way I could just pin it on to the shirt.) The other person wore all white clothes with "1715 AD - 1799 AD" and a light bulb hanging around their neck. What were we? Why, "The Dark Ages" and "The Age of Englightenment".
I've seen a costume for "Quarterback" where you enlarge the image of a quarter and attach it to your back.
Have fun and do tell us what you chose to go dressed as!!!!