It's a simple game, played best with a group of children. Have the kids pair off and stand in two straight lines, with each kid directly across from his partner. Each pair is given a water ball. They toss the balls back and forth; when a ball breaks, that pair is out. Last pair with a ball intact wins. One variation is to have the children take a step back after each throw, making them have to throw farther. Another variation is to have the kids stand in a circle instead of two lines. Make a pinprick in a ball before filling it up with water, and then have the kids toss it around the circle. The last one holding the ball is in for a wet surprise.