There are some fans that act poorly when going into an arena. Of course, there will always be negative chanting on the other team, and plenty of boos for the opponent. However, sometimes, those chants get too far, and cross borders that shouldn't be crossed.
A few years ago, Russell Westbrook had an altercation with a Utah Jazz fan who reportedly said some racially charged words to him during an Oklahoma City Thunder - Utah Jazz matchup. We see Russell Westbrook say "I'll f*ck you up" to a fan who Westbrook later stated said a racial slur towards him.
The fan, by the name of Shane Keisel later sued Russell Westbrook in an attempt to get $100 million dollars in return for what he claimed was "emotional stress". The lawsuit also claimed "defamation". However, a Utah Jazz judge has recently thrown out the lawsuit.
There is no doubt that racial slurs shouldn't be tolerated in the NBA. While most fans behave well, that incident with Russell Westbrook is extremely unfortunate. Based on the video evidence, there is nothing that suggests that Russell Westbrook said or did anything that warranted a $100 million dollar lawsuit, and it seems as though the judge agreed.