I am almost 100% sure that he was throwing a gang sign. He can say whatever he wants about what it means to him, but that was clearly the blood gang sign, and he was clearly mad when he did it. Paul is not a bad guy, but he should not have done that. I have been watching Paul play since he was a freshman in Lawrence, Kansas and if he indeed has done that every game with the Celtics like Ainge says they should have stopped it a long time ago.
Edit. no need for the image imho