This viral sensation is more than a month old, but it fits the theme of the music tournament.    For the uninitiated, Jimmy Fallon, who does a dead-on Neil Young impersonation, covers the new Willow Smith teeny-bopper song, “Whip My Hair” as Young, with backup help from Bruce Springsteen playing a 1975 version of himself.  The concept is deliciously stonerific, and along with this surprisingly funny Glee shtick, has completely recast my conception of Jimmy Fallon.   You’ve gotta whip your hair!