As you are reading, you feel like peeing. You get up, walk to the toilet, pull your pants down, aim, and start. As soon as your pee bursts out, you feel a fart coming, too. While you are peeing, you focus on that fart. But just as you are about to let it go, you feel that something is not exactly right, and you tighten your asshole. It feels kind of wet. Perhaps it is diarrhea? When you finish peeing, you shake off the last drop, turn around, and sit on the toilet. As soon as you open your asshole, you start farting convulsively and squirting loose shit. It was diarrhea! As you are wiping yourself, you keep wondering at it all. Your asshole is a marvel of evolution. And an utterly neglected one.