Summarize the following:
Don't tie it, but don't let air escape.    Alternatively, you can just pop it.

Summary:
Gather a balloon, flour, a funnel and a small spoon. Place the funnel in the balloon. Pour flour all the way to the top of the balloon. Blow half the balloon up. Pour water on the balloon. Let out a quarter of the air. Tie it firmly. Throw at a tree or wall.