Greatest Video Ever! Errant superstar Justin Bieber, who as of late has made more headlines for smoking, reckless driving and going shirtless than for his music, is in on the joke!
He proved that when he allowed actor/comedian Zach Galifianakis to whip his butt -- literally!
The singer participated in this brilliant Funny or Die skit, serving as the guest on Galifianakis' hilariously awkward interview show 'Between Two Ferns.' Not only was The Biebs grilled about what it's lik