Fallon, Crystal, and Seinfeld revisit Abbott & Costello's classic "Who's On First?" routine, where we finally get to meet the team's first-baseman "Who," second-baseman "What," and third-baseman "I Don't Know."

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The Tonight Show Starring Jimmy Fallon features hilarious highlights from the show including: comedy sketches, music parodies, celebrity interviews, ridiculous games, and, of course, Jimmy's Thank You Notes and hashtags! You'll also find behind the scenes videos and other great web exclusives.

"Who's On First?": The Sequel (w/ Jimmy Fallon, Billy Crystal & Jerry Seinfeld)
http://www.youtube.com/fallontonight