Justin Timberlake and Jimmy Fallon Do 'History of Rap Part 3' (VIDEO)

Justin Timberlake is doing the publicity rounds for his new movie "In Time," which means he's been appearing on the talk show circuit. That means he stopped by "Late Night with Jimmy Fallon." And that, of course, means there was a new "History of Rap."

This is the third time Timberlake and Fallon have broken out into a rap medley in the middle of Fallon's show, which officially makes it a tradition. This time, the duo launched into their act before the interview even started: Fallon began to introduce Timberlake, then trailed off, said "screw it," and grabbed a microphone.

Among the many songs that Fallon and Timberlake covered in "History of Rap Part 3" are "Baby Got Back," "Gangsta's Paradise," "Bust a Move," and "Mama Said Knock You Out."

The boys also included a few songs that aren't exactly rap, such as "Harder Better Faster Stronger" and "Killing Me Softly."

So, for your weekend enjoyment, here's two white dudes rapping: