It's been an interesting couple weeks for Justin Bieber.
First, Ke$ha seemingly disrespected the young singer by referring to him as a "baby" (she later apologized).
Then, Bieber may or may not have dissed Mariah Carey.
But Justin did have one clearly positive result over the last few days: his performance on The Late Show with David Letterman. Watch below, as the 16-year old does his thing, followed by a few photos of him outside the studio...