Is this for real? No, seriously...is it?

A while back we heard rumours that Casey Affleck was making a movie about Joaquin Pheonix and his career. And it was going to be kinda weird. JP was doing all kinds of weirdo stunts, like appearing on the Dave Letterman show looking/acting like this. And other strange stuff like that.

So anyway. This documentary is about a lost year in the life of JP, as he quits Hollywood and takes the year off from movies to focus on his rap career.

But is this doc for real? Some say it's a mockumentary and that JP is taking method-acting to the extreme. Of course Casey Affleck and JP both insist it's for real and not a publicity stunt.

What do you think? I'm Still Here comes out September 10 in the US.