During a stand-up gig in Atlantic City, New Jersey, last weekend, an audience member reportedly yelled out the name of Russell's ex-wife, causing Brand to launch into a four-minute rant.
A witness told Life & Style magazine: "This guy randomly yelled out, 'Katy Perry', and at first Russell didn't make much of it. But in a little while, he did it again, and Russell lost it."
According to the inside man, Brand stepped down off the stage and insisted the house lights were turned up so that the guilty party could be pointed out to him.
The source went on: "He tore into him for maybe three or four minutes, standing right there in the middle of the crowd with the lights up."
Russ reportedly told the heckler: "You look like something that's fallen off the side of a church. And what is it that you have rattling around in your mind? Some bizarre combination of alcohol and idiocy. Some cocktail of nothing. And yet you have the confidence to continue shouting."
The witness claims the long-haired funnyman then called into question the man's ability in the bedroom before suggesting he may be impotent.
"Eventually he pulled it together and got back on the stage," the insider added. "And being Russell, he told the guy he'd just tore apart that he loved him."
According to Life & Style, however, other audience members have suggested the heckler was shouting: "God save the Queen."