A little black light, some tonic water, and some Jell-O, and you can have a glowing dessert. It'll will be a treat for the tongue and the mind (mostly for the mind, though).
Boil half the tonic water called for by the recipe, and add the Jell-O, stirring until it's dissolved. Add the remaining tonic water cold, then put it in the fridge and let it sit until it's cooled to solidity. Then break out the black light. The Jell-O should glow.
The ingredient in tonic water that separates it from regular water is quinine. It's an alkaloid that has been used as a potent malaria-fighting drug for hundreds of years. It's also been used to make alcoholic drinks glow in the dark — at least, to human eyes they glow in the dark. Actually, they're receiving lots of ultraviolet light from the black light, and they fluoresce. Most of the time, a material can either absorb or radiate only the wavelengths of light that it receives. Some materials can take in one wavelength of light, absorb some of its energy, and radiate the rest. This is fluorescence. Quinine takes in ultraviolet light, absorbs some of its energy, and radiates light that humans can see — so it glows in the dark.