Twenty-One!

Once upon a time, there was a blonde driving down the highway. In the distance, she saw a brunette doing jumping jacks in the middle of the road, so she decided to pull over.

The brunette was jumping up and down clapping her hands over her head, and shouting, "Twenty one! Twenty one! Twenty one!" So, seeing how this looked like fun, the blonde got behind her, and started doing jumping jacks, and shouting, "Twenty one! Twenty one! Twenty one!"

This goes on for about an hour, and the brunette got tired, so she sat down. But the blonde decided to continue because she was having the best time of her life doing jumping jacks in the middle of the highway shouting twenty one.

Along came a truck and splat! There goes the blonde. Well the brunette got up and went back into the road and started doing jumping jacks and shouting, "Twenty two! Twenty two!"