Try and swallow your tongue.
Helpful hint: Eat a spoonful of Vasoline.
See how fast you can chug a bottle of water.
Stare at someone until they notice, then smile creepily.
Helpful hint: If you see this kid, run. Fast.
Get down on all fours and see the world from your dog or cats point of view.
See how long you can hold your breath.
Helpful hint: Try not to pass out.
Try the cinnamon challenge.
Helpful hint: No hint. Forget I mentioned it.