Jimmy Fallon and Justin Timberlake perform on Friday's Tonight Show.

Of course something special has to happen when Justin Timberlake made his inaugural appearance on "The Tonight Show starring Jimmy Fallon."

The two BFFs presented the fifth installment of the "History of Rap," rhyming their way through just about every hip hop hit you can imagine.

They pay tribute to everyone, from Run DMC and Jay Z to N.W.A. and Kanye West. There isn't a much better way to close out Fallon's first week as host of "The Tonight Show."