I can't stand it! If he wants to sulk in a corner, let him. It's his choice. If he wants to mess up tasks to show off, it's his choice. HMs can't stop him acting like a tit but what they CAN do is stop pandering to the arsehole (Ooooh me language! ).
It's the only way he'll LEARN anything.
It's the only way he'll LEARN anything.