Ranking highly on our costumes to never wear to kids' parties list, the latex serial killer Piggyback costume is as scary as it is hilarious. Thanks to a clever optical illusion, this costume makes it look as though you are being carried away by this terrifying, pint-sized serial killer. Our Piggyback outfits go down a treat wherever they are worn. To get the latex serial killer Piggyback costume ready for action, just stuff the legs with rolled up pieces of newspaper.