I was at a Bills game in Buffalo last year. 5 rows ahead of me was big tall dude, who stood up and would not sit down. This was blocking the view of everybody behind him. People grumbled, but nobody said or did anything for about 20 minutes. I was quite peeved. Then an old lady right behind him gently tapped him on his shoulder and reminded him that he was blocking the view of several people behind him. The dude shrugged his shoulder and said, "not my problem, you can stand up too if you want". I am a mega-nerd, but I lost my cool right there and then and started screaming at the guy. My girlfriend, who didn't want to see me get beat up, pulled me away from the scene.

Many people are just massive assholes. Asking nicely does not work. Particularly big drunk dudes at an American football game. That was my first and last visit to a football stadium.