(NEW YORK) -- It was all a joke. Appearing on the CBS' Late Show Wednesday night, actor Joaquin Phoenix finally admitted to David Letterman that his infamous appearance nearly a year and a half ago -- in which Phoenix sported an overgrown beard, dark glasses and mumbled his way though the segment -- was a hoax. "I was looking for a beat down, and I got one," Phoenix told Letterman. "I want to thank you for that.” Letterman and Phoenix both denied that the late-night host was in on the act. "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," said the clean-shaven actor. "I hope I didn’t offend you in any way." Phoenix pretended to retire from acting and become a rapper for his documentary 'I'm Still Here.'
Copyright 2010 ABC News Radio.