The Steve Bartman Incident: The Chicago Cubs' Moment of Shame

Cubs fans are devoted to their team. They have to be because they only win the World Series every 108 years or so. They're SO devoted that if someone jeopardizes their success, his life will be ruined, like poor Steve Bartman.
In 2003 the Cubs finally made it to the National League Championship against the Miami Marlins. In the 8th inning of game 6 (the Cubs let the series 3-2), Bartman tried to catch a foul ball that might have been playable. A few other guys tried catching the ball too, but Bartman is the one who deflected it, leading the umpire to declare fan interference.
Fans threw pizza at him and poured beer on him, and he had to be dressed as an usher an escorted out of Wrigley Field for his safety.
If Bartman didn't interfere, it would have only been the second out, so he didn't directly cost the Cubs the game. What cost the Cubs the game was that they gave up 8 runs after the incident and lost game 7.