Tension in a football stadium makes it ripe for rude behavior. The NFL has implemented a code of conduct for fans in the stadiums to help combat the rudeness and disruptive behavior of rowdy and drunk fans.
Stress is one of the four main causes of incivility. People tend to act more aggressively and are prone to outbursts that you would not witness under more peaceful and calm circumstances. The other three causes of incivility are: