Chubby Bunny is a game wherein you put a marshmallow in your mouth and attempt to recite the phrase "Chubby Bunny". If you succeed, you put another marshmallow in your mouth. If you fail, you get eliminated. This goes on until participants are overloaded with marshmallows in their mouth, and hilarity ensues. (I used to play this game in summer camp, but if I recall correctly, we used to have to say "I was born on a pirate ship with lots and lots of apples", which was hilarious for a bunch of 12-year-olds).
Sadly, this seemingly harmless game has taken its toll. 12-year-old Casey Fish from Illinois suffocated while playing the game with classmates back in 1999. In 2006, the same thing happened again, this time Janet Rudd, a 32-year-old, died playing the game at a fair in London, Ontario.