A kid at the middle school where I work tried the milk challenge which is to drink one gallon of milk in under an hour and hold it in for 30 minutes. She made it to 9 cartons which was just a little over half way before she barfed. At least she got to go home early.
Don't know if it was this cinnamon challenge, but several years ago America's Funny Home Videos featured some kids eating cinnamon on a dare. If I remember correctly, it was one of the finalists for the big money.