Just about everyone loses their cool once in a while. That's especially true for professional athletes, who are some of the most competitive human beings on the planet. Though the NBA doesn't feature nearly as much violent contact as the NFL, basketball is a physically demanding game that involves a lot of banging bodies and clashing egos at the professional level. That's a formula for drawing out some pretty terrifying displays of anger.
In the NBA, there are essentially two ways for referees to punish players acting out: technical fouls and flagrant fouls. Technicals are often doled out to players engaging in unsportsmanlike conduct, such as arguing with referees or taunting opponents.