Once upon a time, in a land not-so-far-away, there lived a handsome prince. This handsome prince had a beautiful princess daughter. One night, while the prince was putting his sweet little princess to sleep, he was singing to her, her head resting upon his shoulder.
While he sang to her, he patted her little princess bottom. For a moment, he stopped patting her little bottom. In his abscence, Little Princess took her own little hand and patted her own little bottom. Handsome Prince patted again, then stopped, and Little Princess took over.
This switch-back patting continued until Little Princess fell alseep happily ever after... or, until morning, that is.