Sitting in the front row at a basketball game can sometimes end with a player accidentally flying into you. Or it can end with you pretending that's what happened.
This Knicks fan saw Vince Carter get, like, kind of close to him and decided to seize the day. Reportedly, he was yelling that Carter had slapped him. Based on the side of his face he was clutching, Carter must have waited until he was past the guy, picked his arm up and swung it backwards, possibly dislocating it in the process, and done all of this in less than a millisecond so it was completely imperceptible to the human eye.
Vince Carter is a monster of an athlete, but I really don't think he has those kinds of skills.