NBA's Montrezl Harrell Blasts Fan Again, 'Shut The F*ck Up!'

Clippers stud Montrezl Harrell took policing loud-mouth fans into his own hands again Monday ... telling a courtside heckler to "shut the f*ck up, now!"

It all went down at the L.A.-Timberwolves game in Minnesota ... when Harrell's Clips were getting ribbed by some guy with floor seats at the free-throw line.

Montrezl wasn't in the mood to hear it ... and turned to the dude and screamed, "Be a fan, bro. Sit over there and be a fan. Shut the f*ck up, now!"

It ain't the first time Harrell's gone after a heckler ... back in December, he threatened to "smack the sh*t out" of some guy who was chirping at him on the way to the locker room.

Of course, Harrell's one of MANY who have had incidents with fans this season ... guys like Kevin Durant and Blake Griffin have hit back hard at smack-talking guys in the stands.

Doesn't seem the clapbacks are ending anytime soon ... but if anybody wants to learn how to calmly deal with the situation -- don't forget Julius Randle's advice!!!