Video: Justin Timberlake and Jimmy Fallon's 'Rapper's Delight'

You never know when Justin Timberlake might break out into song!

The singer-turned-actor joined Jimmy Fallon on "Late Night" and was so taken by the show's house band The Roots that he couldn't help but drop some rhymes. The two started out rapping to the Sugarhill Gang's "Rapper's Delight," and from there the performance turned into a medley of rap and R&B renditions.

From Eminem's song "My Name Is" to T.I. featuring Rihanna's track "Live Your Life" to Kanye West's "Gold Digger," Timberlake and Fallon performed a slew of hits.

Meanwhile, ET caught up with Timberlake to get his take on breakout rapper, Nicki Minaj. "She's very talented," he told ET while at a screening for 'The Social Network.' "It's cool to see young females sort of do really well in hip-hop as well."

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