The girls LOVE to play with shaving cream in the bathtub; I had to work up the courage to add in the food coloring to make paint like Having Fun at Home did. I don't know why I was so hesitant, As long as you clean immediately after it doesn't stain the tub. It does however stain children. Luckily the girls weren't too worried about the pink hands!
This kept them busy for quite a while, but they practically needed another bath by the end. I would definitely recommend playing first, rinsing off the tub and then bathing.