Joaquin Phoenix`s rapping career was for a rockumentary

Updated: May 08, 2010, 17:12 PM IST

London: The real reason for the bizarre behaviour of Academy Award winning Joaquin Phoenix has been revealed. It was all for a `mockumentary` which will soon hit the theatres.

The `Walk the Line` star has been touting a secret project, a mockumentary filmed by brother-in-law Casey Affleck, to Hollywood bigwigs, reported Sun online.

Back in October 2008, Phoenix sparked health fears when he announced his retirement from acting and the launch of a career as a hip hop artist and grew a bushy, unkempt beard. The following January he performed a disastrous rap at a Las Vegas venue before falling off the stage and a month later he gave an incoherent, mumbling interview on David Letterman`s Late show.

The weird shenanigans filmed by Affleck forms the basis of the new movie, which was screened earlier this week to industry buyers including Harvey Weinstein.