Jimmy Fallon, Jerry Seinfeld, Billy Crystal do "Who's on First?" routine on "Late Night" Jimmy Fallon recreated Abbot and Costello's classic "Who's on First" routine on Thursday's episode of "Late Night with Jimmy Fallon," with the help of some very well-known guest stars. Jerry Seinfeld and Billy Crystal both took part in the baseball-themed bit, donning old-fashioned uniforms and playing two of the uniquely-named infielders for the St. Louis Wolves. The two stars are both big baseball fans -- Seinfeld cheers for the New York Mets, while Crystal roots for the Yankees. This updated version of the routine featured the first, second and third basemen, named Who, What and I Don't Know, respectively. Steve Higgins played the bewildered baseball fan, while A.D. Miles played the second baseman. Tell us: What do you think of this new version of "Who's on First"?