The pair, who are promoting this year's Blended, their third film together, were accompanied by Fallon on guitar as they crooned about their shared on-screen history.

But Sandler couldn't resist throwing in the odd cheeky gag, encouraged by a giggling Barrymore (who is five months pregnant) and whoops from the delighted live audience. "I will still love you when your boobs are on the floor," he replied to her line - "I will still love you when you're 64."

At another point Barrymore sang, "I still remember the first time I met you", with Sandler joking, "You gave me a hug and I got a boner."

"Every ten years I promise to love you," said Barrymore, later branding Sandler her "best movie husband" - and when grilled by him, admitted he was "much better than" her other co-stars Hugh Grant and Ben Stiller.

The two actors sealed their cracking performance with a kiss at the end of the song.

Adam Sandler's song tribute to co-star Drew Barrymore