You have to see this video! God bless David Letterman, he is so great. We don't know what's been going on with Joaquin Phoenix lately. He announced that he was retiring from acting to persue a rap career. He's been seen in clubs looking like he's drank an entire keg or taken one too many.. special pills. It's awful! Do we think this is all a publicity act? Well, check him out on his appearance on The David Letterman Show. We couldn't help but squirm in our seat, this isn't the Walk The Line actor we remembered and loved! He is just seriously out of it, what's the deal?!