Justin Timberlake And Jimmy Fallon RAP TOGETHER in "History of Rap 2" on Late Night

The singer-turned-actor went on Late Night with Jimmy Fallon Tuesday to promote his new movie, Friends With Benefits. Everyone expected him to do a follow-up to last September's now-viral "History of Rap," where he spit out rhymes from Tupac to Jay-Z with Jimmy.

“It’s not going to happen — we can’t do it again,” Justin Timberlake told Jimmy and his audience.

But, of course they did. Beginning and ending with Kurtis Blow's "Breaks," the two worked their way through everything from Grandmaster Flash and DMX to Biz Markie and Vanilla Ice. The mash-up was really well-reherased - or at the very least, it sure looked like it was.

Watch the video below....