While that remains my favorite rendition of the song, this one comes close for being almost the most surprising and funny, as well.
It comes from an appearance Julia Louis Dreyfus made on Late Night with David Letterman in 2000. She leaves the desk to perform a number, which turns out to be "16 Going on 17" (and does solidly well at it, having fun along the way.) When all of a sudden, who should join her on stage but Jerry Seinfeld. You can imagine the audiences's reaction...
Well, no, you don't have to imagine it. Here's the video. The question though in the audience's mind, as he stands there staring at her, is what in the world is he going to do?