The Social Network's antihero may win the award for the comfiest Halloween costume out there. To capture the look head to toe, don a sweatshirt (if you have an old '90s Gap one, even better), sweatpants or jeans, and the clincher: Adidas flip-flops. If you want to go the extra mile, get business cards made that say "I'm CEO . . . bitch" to pass out. Bonus: your getup is the perfect excuse to check Facebook throughout the night.