Joaquin Phoenix's famous friends Sean Combs and Ben Stiller were both "in" on the joke during the filming of his hoax movie I'M STILL HERE.
The Hollywood actor hit headlines in 2008 when he sensationally announced he was quitting acting to take up a new career as a rapper.
Phoenix's brother-in-law, Casey Affleck, filmed the star's bizarre antics for the 'documentary', which they later admitted was an elaborate hoax.
Both Combs and Stiller appear in the movie, and Affleck has confessed they were both fully briefed about Phoenix's fake persona.
Speaking in the DVD commentary to accompany the movie, Affleck says, "Puff (Combs) was great. He invited us over to his house, and we actually went over and we explained what the movie was to him and you know, sat with him for about a half an hour and sort of talked him through it. And all he said was that he was in. Puff... took direction very well."
Referring to Stiller, he adds, "He was totally game."