Possibly my all-time favourite was a really bizarre one. Joe Bugner was fighting someone (can't remember who) and the other guy caught him with a really low punch. While the referee was giving this guy a long lecture in his corner, Bugner was standing in his own corner, glaring at his opponent like he wanted to kill him. So the ref says 'box' and Bugner stalks over and takes the guy out with one punch. Just like that. It was hilarious.