I may be biased, but here's how this scene looked to me: Chicago Bulls forward Carlos Boozer stuck out his elbow as Atlanta Hawks forward Josh Smith descended from a third quarter dunk, popping him in the neck-and-shoulder area. Smith reacted aggressively, leading Boozer to whirl around and bellow something to the effect of, "Who the f--- you pushing" or "What the f---'s your problem" or "Face your pain!" Probably not the latter.
The video by @jose3030:
And a gif via @blazersedge of Boozer's reaction:
Earlier in the game Boozer's forehead was opened up after some vigorous contact with Zaza Pachulia. He had to step off the floor twice due to referee's timeouts to clean the blood, so of course he's a little extra testy. The Chicago crowd has taken to booing Smith every time he touches the ball or re-takes the floor. Whatever.