Instead of water balloons make sponge bombs! This is a great way to beat the heat without using up a lot of water, and sponge bombs can be used and re-used all Summer long. (And don't have all those balloon pieces everywhere!
Neat idea for a kid's birthday party, tie balloons to favor bags. They will be festive party decor, plus every kid wants to take home a balloon! "This really works! The kids love them so much they almost fight over which color they get to take home!