The following is from Wikipedia.org. This is good. Wait until you see the set of examples of violence.
Violence in sports can result in chaotic brawls, both by athletes and spectators. They may involve beer bottles, sinks from stadiums, improvised stabbing utensils, stadium seats, and whatever else may be found on hand.
In sports which are inherently violent, violence which goes beyond what is permitted by the rules sometimes occurs.
Competitive sports, such as football, basketball, and baseball may involve aggressive tactics, but actual violence is considered to fall outside the boundaries of good sportsmanship. Contact sports such as American football, ice hockey, rugby football, boxing, wrestling, and water polo involve certain levels of physical violence, but include restrictions and penalties for excessive and dangerous acts of force. Violence in sports may include threats, or physical harm and may be carried out by athletes, coaches, fans, spectators, or the parents of young athletes.
George Orwell once made the observation, “Serious sport has nothing to do with fair play. It is bound up with hatred, jealousy, boastfulness, disregard of all rules and sadistic pleasure in witnessing violence: in other words it is war minus the shooting.”
Here’s the full article.