File under "disgusting but true."© Maki Naro

Saliva serves a whole mess of purposes. It aids digestion, lubricates your mouth, and even acts as an ion buffer, which keeps minerals in your teeth from dissolving and salts from precipitating in there.

If you're a certain member of the swift family, you may use your spit to build nests. Weird people might eat your nest. Such is life.