Affleck Admission: Confused Joaquin Phoenix Was a 'Performance

Anyone who saw Joaquin Phoenix's jaw-dropping appearance on David Letterman's show in 2009 hoped for the best and expected the worst: hoped that Phoenix was acting at least a little, and expecting that the Oscar-nominated actor had simply lost his marbles.

And for over a year conspiracy theories have outnumbered answers about the appearance and the mental state of the actor.

Now there's an answer.

(But first, in case you forgot)

It was all a hoax. Or more specifically, it was all a publicity stunt.

In an interview with the New York Times, Casey Affleck (brother of Ben) admitted that his new movie, "I'm Still Here," which he directed and starring the maybe-he's-crazy-maybe-he's-not Phoenix, was a "mockumentary," satire, hoax.

"It’s a terrific performance, it's the performance of his career," Affleck said of Phoenix. He also added that he never meant for it to be a hoax ("The idea of a quote, hoax, unquote, never entered my mind."), but never explained how he expected an actor living in character for over a year-and-a-half would not be considered such a thing.

The movie follows Phoenix from childhood (using fake home movies, save for one) to adulthood, where he gives up acting for a rap career and develops a drug addiction (among other things).

Phoenix has been silent about his Letterman appearance and his fake life. And Affleck clarified that Letterman was never in on the charade. More answers could be available next week, when Phoenix is slated to be on the show again on Wednesday. Will he be in "character" then?

"No, no, no," Affleck said emphatically.