I've never been one for schoolyard violence (my core isn't strong enough to withstand a punch), but a good schoolyard insult is an under-appreciated craft. The classic ones still cut deep. If someone puts an L shape to their forehead and sticks out their tongue, it hits harder than any well thought out insult could. Because children can be exceptionally cruel. They don't have time to faff about with high falutin language, psychoanalysis, and guilt trips. No, they will immediately find the surfa…