Courtesy of ParentHacks (which is a pretty fun site):
Toss a couple of glow sticks in the tub, and turn off the lights. Voila, a multicolored glow-in-the-dark bath!
What a blast. And glowsticks are only about $0.99 now so it’s cheap fun for little kids.
But gee, you think the guy who thought that up ever partook of recreational pharmaceuticals?