Whirlyball is a game played on bumper cars where two teams using track balls attempt to score goals against one another by throwing the Trac Ball into the opposing team's elevated net.
The grooves in the racquet along with the striations on the ball provide a great deal of spin which allows players to throw deep curveballs with little effort.
Holding the racquet perpendicular to the ground and throwing forward will cause the ball to spin backwards towards the thrower.
A more dramatic curving effect can be caused by holding the racquet parallel to the ground.
Early versions of the Wham-o sets included two extra Styrofoam balls.