We spoke with the comedian -- who knows a thing or two about getting an earful from fans -- and he tells us the best way for Russ to shut 'em up is to elevate his game.

Of course, it's been a rough year for Westbrook in his first season with the Purple and Gold ... and spectators (L.A. especially) have been giving the former MVP a hard time.

Russ' numbers have dipped -- he's struggled to shoot the ball from the perimeter and at the free-throw line and is among the league leaders in turnovers.

Most recently, Russ pled with fans to stop calling him the name "Westbrick" ... saying he often let it slide, but it's to the point where he wants it to die.

But, even that didn't stop fans from rolling up on Brodie in the street -- A fan recorded himself telling Russ he wants him to play better, but the All-Star guard wasn't feeling it all.

Jim tells us Russ needs to start going back at fans in a war of words -- encouraging the baller to "attack these losers" who are yelling at him.

Jim said there are plenty of nights in his industry he doesn't bring it, so he never gets mad at fans for heckling him if he deserves it.

"Well that's why I said, 'play better,'" Morton says, "because if I'm on stage, there's plenty of nights when I suck."

"I kind of know when I suck. So if I'm having a really bad set and someone yells, 'you suck,' then I'll address it, and I'll be mean to the person."