Since he was younger than me and obviously had problems I always tried to be nice to him, but damn if he tested my patience. He ALWAYS tried to cheat- every time he had the opportunity to attempt it, he pulled these transparent attempts to break the rules, in any game. In 40k his army lists were always exceeding the game's point value, so I had to waste time every time we played going through his list and totaling his point values to see how much he was cheating (which was doubly annoying, since he played Tau, which I am unfamiliar with, so I had to keep leafing through the codex). Speaking of Tau, when he first started playing 40k with us, he informed us he was going to buy them as his army. We approved, and a few of the more experienced players asked to see what he was buying. His Tau army did not have a single fire warrior, instead he bought mass amounts of Kroot. Now, I know some people like to make Kroot-themed fluff armies, but this kid kept insisting he would win every game with his massed Kroot. Despite our protests he payed for them, and then in the first game he played, a Chaos player fucking wrecked them with bolters, hardly taking any damage at all. The kid got this awful look on his face, started mumbling about he was a failure, and sat in the corner for the rest of the session.
It's good not to be in high school anymore...although now I don't have anywhere to play 40k.