It was the talk of Hollywood. Over a year ago Joaquin Phoenix shocked viewers of David Letterman's show when he turned up with sunglasses and a long beard, and mumbled his way through the interview.
This week, he returned to David's sofa. And he had an apology for the TV host.
"I hope I didn't offend you in any way," he told the presenter on Wednesday night. "I mean, I think that you've interviewed many, many people and I assumed that you would know the difference between a character and a real person."
Joaquin's incoherent appearance on the show was in fact a send up, all for Casey Affleck's documentary, I'm Still Here.
The friends wanted to make a film about the idea of celebrity and the media, and decided to create their own version of reality TV.
It began with Joaquin announcing his retirement from the world of acting.
"We didn't really know how the media was going to respond," he said.
"When I first made the announcement – which I thought in itself was a joke, a 35-year-old saying he was retiring – I didn't really know if anyone would care.
"I assumed they wouldn't, but it kind of snowballed and became this big thing.
"Then I came on the show and that got a lot of attention."
But David insists he wasn't in on the act.
"Was there a script that you and I were working with?" he asks Joaquin during his show. The actor responds with: 'No'."
After the appearance, Joaquin kept up the pretence, abandoning his acting career to concentrate on his faux career as a rapper.
One gig in particular made headlines, when the actor jumped off the stage and began scuffling with a heckler, after telling him: "I've got a million dollars in my bank account, what have you got?"
But this was all part of the put on – the man in question was a friend, he has now revealed.