Chili and wasabi—as well as menthol, fizzy drinks, and hot and cold beverages—contain molecular compounds that stimulate the pain receptors in our nerve cells, invoking a simulation of what would happen if someone actually lit a flame in your mouth. In chilies, the molecule capsaicin creates a hot burn, turning your mouth into a blazing inferno. Isothiocyanate molecules in wasabi, mustard, and menthol cause a cold burn, searing up your nostrils and making you feel like your head will explode, or as one Reddit reader put it, "It's like my scalp is being pulled back and the inside of my nose is being stuffed with chopsticks."

Plants developed these molecules in a tactical evolutionary move to deter animals and humans from eating them. But we as humans conditioned ourselves into liking the very sensations that were engineered to repel us. Hell, we aren't at the top of the food chain for nothing. According to Paul Bloom, Yale psychologist and author of How Pleasure Works: The New Science of Why We Like What We Like, "Philosophers have often looked for the defining feature of humans: language, rationality, culture, and so on. I'd stick with this: Man is the only animal that likes Tabasco sauce."