My special unisex Playa MacGyver emergency costume starts with a paper jumpsuit used by painters, dirt cheap at any hardware store. They are super light and zip up the front, easily slipping over multiple layers of nocturnal hides or you midday bare ass. Leave it white and call yourself a marshmallow, null set, sperm, etc. or customize a special outer skin with markers, paint, crayons, or what not.

I will post pics of my two favorite variations on this model, both easy and extremely interactive: one is the HUMAN GRAFFITTI WALL, where you carry a fanny pack of markers and let people write stuff on you. Always a unique look, but usually unpredictable.

My best costume ever cost me $1 and lasted a decade of Halloweens before shredding and reconstructed at Burning Man. I call it MISTER TWISTER. Using red, blue, yellow, and green magic markers and a simple thin cardboard template & backboard, I made four rows of large circles up the legs, back and chest of the suit, then copied the red box logos for 'Milton Bradley' and 'Twister' down the sleeves. The outfit is completed with an actual spinner from the game fitted with a cord and carried around the neck. To activate, just say these four simple words - "Want to play me?"

little boy's children's costumes are H.O.T. on sexy chicas:
instead of paying 50-60 bones for a sexy-ass adult costume such as construction worker, doctor, etc... you can pay well under 20 bucks for a kids version which you modify slightly to be a mini outfit.