Donte DiVincenzo was caught on camera telling a fan to 'shut the f*** up' during the Knicks' loss to the Bulls on Friday.
The supporter, sitting courtside at United Center, shouted out to the New York guard mid-game, telling him to tuck in his jersey.
DiVincenzo, visibly annoyed by the comment, turned around and gave the fan a piece of his mind.
His R-rated response drew laughter and cries from other members of the crowd. 'Come on, you can do better!' one shouted.
The original heckler, who also appeared to be filming the clip, continued to wind up DiVincenzo by reminding him that he was flouting NBA regulations.
Donte DiVincenzo was seen telling a fan to 'shut the f*** up' during the Knicks' loss to Chicago
'I mean, it's a rule in the NBA,' they shouted. This time, however, the Knicks player did not respond.
Official NBA rules state that 'while playing, players must keep their uniform shirts tucked into their pants, and no T-shirts are allowed.'
DiVincenzo scored 10 points - his lowest total since January 17 - as Javonte Green had 25 points and 13 rebounds for his first career double-double to help the Chicago Bulls to a 108-100 win.
Chicago (37-40) moved one game ahead of the Atlanta Hawks for the No. 9 seed in the Eastern Conference and home-court advantage in a play-in tournament game.
New York (45-32) remained tied with the Orlando Magic for the fourth-best record in the East.
The Bulls never trailed while overcoming the third straight double-double for New York's Jalen Brunson, who had 35 points and 11 assists.
DiVincenzo scored 10 points - his lowest total since January 17 - as the Knicks were beaten