Several years ago, when I was still in the Army, a young private in my company did something highly unusual. (Caution: This is gross.) He posted a picture of human excrement — his own, presumably — on Facebook with the caption: “I’m da shit.” Now, suffice it to say, this guy was not an academic stud, and I had witnessed him do plenty of odd things before. But if the intent was to offer proof that he was, as he claimed, “da shit,” the accompanying photograph didn’t just undermine that goal, but also marked him as a soldier who might benefit from psychiatric attention. He must’ve understood this. Strange as this guy was, he was no lunatic. So why did he do it?