The traditional Japanese women entertainers known as geishas once wore heavy white makeup containing toxic lead and zinc, which damaged their skin. As a remedy, they applied a face mask containing a somewhat distasteful ingredient: nightingale droppings. The birds' poop, as it turns out, contains enzymes that are said to break down dead skin cells and guanine, which supposedly gives the complexion a warm glow.
The Shizuka New York Day Spa offers a modernized version of the regimen, in which the droppings are first drenched in ultraviolet light to sanitize them and then mixed with rice bran. The rice bran exfoliates the skin. The hour-long treatment costs $180 [source: Shizuka].