A surreal sit-down with David Letterman has left everyone wondering whether actor 'Walk The Line' star, Joaquin Phoenix, was playing an elaborate prank or was he seriously stoned.

While, Mike Bruno of Entertainment Weekly writes: 'For the record, I still think the whole thing has to be a joke. But . . . I can definitely see how this could be a fun ride.' TMZ. com insists they are in on the scam and Phoenix together with brother-in-law Casey Affleck staged the squirm-inducing tete-a-tete with Letterman for their documentary.

Phoenix on Letterman's show to promote 'Two Lovers', his new flick with Gwyneth Paltrow, soon joined the ranks of Most Memorable 'Late Show' guests, such as, Farrah Fawcett, Crispin Glover and Madonna.

Attired in a disheveled suit, shades, and a beard, Phoenix fidgeted, chewed gum, answered Dave's questions in monosyllables, appearing totally out of it during his
10-minute interview. Frustrated, Letterman cracked: 'Yeah, I'll come to your house and chew gum,' causing Phoenix to stick his wad of gum under Dave's desk.

Known for his cutting wit, Letterman concluded the interview with: 'Joaquin, I'm sorry you couldn't be here tonight,' an interview that left Letterman and fans wondering whether the two-time Oscar nominee had lost his marbles, completely.