Your lungs take in oxygen, and expel carbon dioxide. Every time you breathe: in comes the oxygen, and out goes the carbon dioxide. But how do your lungs know the difference? At any moment, they could get confused and start taking in carbon dioxide and expelling oxygen. Or what if they get really confused, and start taking in Boston terriers and expelling George Foreman grills? Imagine if, right this very minute, your lungs started taking in lightning and started expelling 1967 Ford Mustangs. Wouldn’t that fucking rule? Oh my god, that would be so awesome. But forget it, because lungs are stuck in that whole oxygen-carbon dioxide rut. Get a life, lungs.