Justin Timberlake was a guest on Late Night With Jimmy Fallon, promoting his film The Social Network, when he and Fallon broke out into a rap medley. The only thing funnier than Fallon asking if the ...

Before "Late Night" began Thursday night, viewers got a surprise clip of Jimmy Fallon, The Roots, and Robin Thicke playing a cover of the summer hit "Blurred Lines" with kids' instruments. Members of ...

Backstage before the show, Jimmy, Mariah Carey, and The Roots grabbed some instruments you'd find in an elementary school classroom and stopped by the Late Night "Music Room" to sing Mariah's holiday ...