One of the real joys in Jimmy Fallon's late-night run has been the Roots' choices of jokey, thematically appropriate walk-in songs for Fallon's various celebrity guests: "Da Butt" for Serena Williams, "Hi Hater" for Bill Hader, that sort of thing. According to bandleader ?uestlove himself, the only song choice Fallon ever vetoed was "She Blinded Me With Science" for Katie ...