It's been shown that the act of smiling has a positive emotional effect on the smiler. It therefore stands to reason that any device which constantly reminds us to smile must be good for us. Enter the Happiness Hat. A sensor measures whether you're smiling or not, and if the answer is no, you get jabbed in the head with a metal spike.
Says Lauren McCarthy, the inventor of the device, "I'm not suggesting we stab people until they smile. I'm interested in whether technology can teach us to be more human."