Rihanna Allegedly Heckles Kevin Durant During NBA Finals

Rihanna was ON FIRE during Game 1 of the NBA Finals -- allegedly heckling Kevin Durant, bowing to LeBron James ... and talking trash to haters on the way out of the arena.

FYI, RiRi is a HUUUUGE Bron fan -- and can be seen bowing to #23 while sitting in her courtside seats at Game 1 on Thursday night. She later dabbed at someone who reportedly told her to sit down.

But the craziest part of the game was when Rihanna seemed to have screamed "BRICK" at KD during a free throw. He made the shot and stared in her direction as if to say, "Got something to say now?"

KD was asked about the incident by BSO's Robert Littal in a post-game presser -- but insisted he didn't remember throwing the eye-daggers in Rihanna's direction.

Sure ...

After the game, Rihanna snapped back to a Cavs/Bron hater -- "It doesn't matter bitch. The King is still the King."