Chicago Bulls player Nikola Vucevic will have to cough up some dough for giving somebody the middle finger during Wednesday's game ... getting hit with a $15K fine for the "obscene gesture."
The 6'10" center was pissed when a ref called him for traveling in the 1st quarter of the Bulls vs. Pelicans matchup ... and was so fired up, he let the middle finger fly.
Unfortunately for Nikola, the cameras caught the 2-time All-Star red-handed on the broadcast ... pretty much solidifying an impending punishment.
Joe Dumars -- the Executive Vice President and Head of Basketball Operations of the NBA -- announced the penalty on Friday .