"jakdedert" wrote in message
...
Much simpler: Put a little dry ice in a plastic drink bottle, like bottle
water comes in.

Add an inch or so of water. Cap tightly. Run away!

The 1/2 liter bottle will swell up to the size of a football before
exploding with a bang reminiscent of shotgun blast...very loud. Sometimes
it takes a few minutes, sometimes longer. If you don't use enough dry
ice,
it only swells. Don't touch it, it could still blow. Throw a rock at it
first, or just leave it alone..

Skiers have been known to use these contraptions in 2-liter drink bottles as
home-made avalanche bombs. One twist - they use urine instead of water to
initiate the blast (more available on a frozen moutainside).