Rips Kyrie Irving Over Vax Stance

Howard Stern just went OFF on Kyrie Irving ... calling the NBA superstar an "idiot" and a "douchebag" over his anti-COVID vaccine stance.

The radio icon laid into the Brooklyn Nets guard in an epic rant on his SiriusXM show ... explaining he cannot wrap his head around Irving's refusal to get -- and promote -- the shots.

"In terms of idiots, he's got to be the top idiot in the country right now," Stern said of Irving. "Guy's got a chance as a young man to make millions of dollars, all he's got to do is get vaccinated but he doesn't want to get vaccinated."

Irving was just barred from both Nets practices and games last week because he won't get the vaccine ... and in a rambling social media…