Justin Bieber was just driving through Beverly Hills -- minutes ago -- when he had his driver flip a bitch in his pimped out Rolls Royce and put down the back window so the 20 year-old pop star could meet 81 year-old talk show host Larry King and shake his hand.

Our photographer witnessed it all -- in fact, as Larry walked across the street, the X17er yelled out, "Hey, Justin Bieber's trying to meet you!" King gave our guy a quizzical look and the photographer explained, "That's Justin Beiber in that car -- he just turned around to come back to meet you!"

Larry's pretty good at keeping up with the news (it's his job, after all) so we assume he knows who the chart-topping heartthrob is and we also assume he'd KILL to have the young music mogul on his Hulu show Larry King Now. King better get his bookers on the phone, stat!