Larry David seemingly tells his old friend Robert F. Kennedy Jr. to kick rocks in his new Barack Obama-produced HBO sketch comedy show "Life, Larry and the Pursuit of Unhappiness."

In the latest episode of the series, Larry dresses in drag as Dora Salk, the mother of virologist Jonas Salk -- the man behind the first successful polio vaccine. As he works on his vaccine, a very tan and critical neighbor with a gravelly voice whose name is Bobby rips into him, saying, "That vaccine’s gonna kill people. It’s gonna give them heart attacks!"

Larry -- as Dora -- immediately fights back, yelling ... "Drop dead, Bobby. You should die a dog’s death. You don’t know anything about science, you’re not a doctor."

Bobby -- who clearly resembles RFK Jr. -- then bites back, declaring if he were in charge, he'd "make sure that no kids took that vaccine" -- including for measles.

Dora doesn't hold her tongue at all, arguing ... "If you were in charge, God help us all! If some idiot, some moron, ever put you in charge, that would be a dark day for humanity."

It's a not-so-subtle jab on Larry's part, who has been openly critical of the current administration and whose friendship with RFK Jr. seemingly hit the trash can when he was named Donald Trump's Secretary of Health and Human Services. As you know, RFK Jr. has been a prominent anti-vaccine activist despite recently saying he's not totally against them.

ICYMI, Larry and RFK Jr. were once super tight -- and RFK's wife, Cheryl Hines, played Larry’s wife-turned-ex Cheryl on 12 seasons of "Curb Your Enthusiasm." Larry even introduced Hines and RFK.

But, it seems their political differences finally took an axe to their friendship. Hines even said she and Bobby stopped speaking after 'Curb' ended, reasoning ... "I think he’s mad [that] Bobby’s in the administration."

Plus, Hines is the only 'Curb' cast member who has not appeared in "Life, Larry and the Pursuit of Unhappiness."

Larry may have changed his heart on RFK Jr. and his devoted wife, but he certainly hasn't let up on using the Trump admin as the butt of his jokes!