Spew

Equipment:
ALKA-SELTZER and some carbonated clear drink... such as Sprite, 7UP, maybe Ginger Ale, or Squirt

Play:
Tell each of your participants to place a single ALKA-SELTZER underneath their tongue. Don't worry.. they won't be able to taste or swallow it with it under the tongue.
Now... give them each a cup of the clear carbonated drink. Fill it with about 3 or 4 ounces. The OBJECT is to see who can hold it in their mouth the longest, but trust me, it will EXPLODE and SPEW out of their mouths! I wouldn't advise swallowing it. It won't hurt them but...YUCK! They must have at least a couple ounces in order for it to work... though it is not about how much they can "drink." It's about how long they can hold it.