Justin Bieber is a huge prankster, but it's good to know he's comfortable poking fun at himself, too. Last week, not only did the 17-year-old pop star joke around on the 'Late Show With David Letterman,' but he also teamed up with Jimmy Fallon to debut a hilarious mock commercial for his Someday perfume.

Justin's official fragrance ad has received some flack for being overly dramatic, so while in New York for a promotional stint, the singer stopped by 'Late Night With Jimmy Fallon' to premiere an, um, alternate version of the spot.
In the black-and-white clip, the two funny guys take turns whispering at the camera. "Someday ... We'll be together. Someday ... I'll be next to you," Justin says, before adding, "Someday ... I'll be older ... Fatter."

Jimmy enters the scene dressed like an older version of Bieber, and says, "Someday ... You'll look like this." He points to himself as Justin asks what happened. "You just got busy ... your metabolism changed a bit."

Oh, and it gets better. Watch the full 'Someday' commercial spoof below. What do you think of the clip?

Check out the spoof on our Video Pick of the Day, or Youtube!