Watch Adam Sandler Serenade Drew Barrymore's Boobs

'I will still love you when your boobs touch the floor,' Sandler sang to his co-star on Wednesday's 'Tonight Show.'

Adam Sandler and Drew Barrymore are pals from way back. The on-screen couple ("The Wedding Singer," "50 First Dates") dropped by "The Tonight Show" on Wednesday night to plug a new movie, but judging from their body language, it was hardly work at all.

Playfully teasing one another and joking about how Sandler's black eye was a result of him getting a bit too close of a look at his "Blended" co-star's pregnant belly, the pair joined host Jimmy Fallon for a touching duet about their enduring showmance.

"Every 10 years we get to fall in love again," said Barrymore, who is pregnant with her second daughter. "We really do," Sandler seconded. "We enjoy it. We have a lot of fun together."

How much fun? Well, they wrote a song about it and here's how it went.

"Every 10 years, I promise to love you," Barrymore began, with Sandler responding, "I'll always be true, even as we get older."

"I still remember the first time I met you," she sang. "You gave me a hug and I got a boner," recalled Sandler. And while Drew said he made her laugh in "The Wedding Singer" and dubbed him the Fred Astaire to her Ginger Rogers, Sandler sweetly whispered, "You're the Rob Ford to my crack cocaine."

Adam made her promise that he was a better movie husband than Hugh Grant, Ben Stiller, or, yes, Fallon (who starred with her in "Fever Pitch.") "I will still love you when you're 64," Barrymore said. "I will still love you when your boobs touch the floor," Sandler pledged.

"Every 10 years you'll always have me," they crooned together, before Sandler hit the classic "Wedding Singer" line, "Oh, I could be the man who grows old with you. I want to grow old with Drew-y!"