The last time Justin Timberlake visited Jimmy Fallon on Late Night, the two performed a hilarious medley of old school hip-hop hits in "History of Rap," a bit that pretty much immediately went viral. Timberlake and Fallon reprised the routine last night, much to the delight of the show's intensely enthusiastic studio audience. The duo picked up where they left off in the late Eighties and summed up the past two decades of rap with snippets of hits by Public Enemy, N.W.A., Salt-n-Pepa, Cypress Hill, DMX, Outkast, 50 Cent, Lil Wayne and Rick Ross. The sing along version of Biz Markie's "Just A Friend" is particularly charming, but it's sorta weird that major icons such as Eminem, Jay-Z, Snoop Dogg, Kanye West, Missy Elliott, the Fugees, the Wu-Tang Clan and the Beastie Boys didn't make the cut. Then again, they may be saving that stuff for "History of Rap, Take 3."