19x91 - Late Show with David Letterman

Dave welcomes musician Justin Bieber and actor/comedian Michael Ian Black. Top Ten Summer Blockbuster Films About Presidents. Can the Biebs sing opera? Dave and Paul do their best to make Justin Bieber an opera star. Now that he's graduated from high school, will Justin Bieber be heading off to college? Justin Bieber shows Dave the new tattoo he got in honor of his new CD, "Believe." Justin Bieber talks about celebrating his 18th birthday. Plus: does this mean he'll get out and vote?