Derek, Hansel, and Valentina Valencia From Zoolander 2
What to wear: Get wigs to match each character's iconic hairdo, and then wear a monochromatic outfit in either all red, all gray, or all green.
How to act: Get ready to layer on the crazy as thickly as you do the hair gel if you head out on Oct. 31 dressed as the fashion industry's most hilarious trio.