Rub-a-dub-dub

I remember sometimes when we were taking baths, we would get out and run around the house singing, chanting really, "RUB-A-DUB-DUUUUUB, RUB-A-DUB-DUUUUUUUB" I think Amber originally started it, but I only remember Cindy and I doing it a couple times. It was fun running into the living room where the rest of the family was probably watching a movie or tv or something. Amber or mom, you will have to elaborate on how this "tradition" was started!