A clean-cut Joaquin Phoenix apologized to Late Show host David Letterman Wednesday for his bizarre appearance on the program last year, which was intended for I'm Still Here, a mock documentary about the Walk The Line star quitting acting to become a rapper.

PHOTOS: Joaquin Phoenix's Arrival and Departure from the Late Show

A disheveled Phoenix appeared on Letterman’s February 11, 2009 broadcast and ranted incoherently about his rap aspirations. On Wednesday, Letterman told Phoenix his behavior was "like you slipped and hit your head in the tub."