John McEnroe could have been one of the greatest tennis players ever. When he was on his game, it was beautiful to watch.  But sometimes he was his own worst opponent.  His on-court behavior and antics were infamous. He would argue with and curse umpires, linesman, camermen, and fans.  He would stall and rage and carry-on, often to drain his opponent of energy and momentum.   He is the only player to have ever been thrown out of a Grand Slam for on-court misconduct.  He is now a famous TV commentator and a leading player on the Champions Tour (retired legends), where sadly his rude behavior and poor sportsmanship sometimes continues.   Today, he often does TV commercials where he parodies his famous blow-ups.  Here is a classic.