Justin Timberlake was in a comedic mood last night in NYC as he inducted Madonna into the Rock and Roll Hall of Fame.

He recalled how she once ordered him to drop his pants to give him a vitamin B12 shot while collaborating on her new album Hard Candy.

“She gave me a shot in my a– and looks at me and says, ‘Nice top shelf,’” he told the audience. “That was one of the greatest days of my life.”

Timberlake also took a jab at his ex, Britney Spears, while inducting the Material Mom.

“She has still found time to kiss someone I may or may not have publicly kissed myself while I was in the audience,” Timberlake said of Madonna. “Of course, you know I was talking about Sean Penn.”

Timberlake punctuated his remarks with, “The world has always been full of Madonna wannabes, and I might have even dated a couple.”

Look at those arms!!

2 more pics – plus VIDEO of Justin & Madonna after the jump!