Tropic Thunder star Ben Stiller had the starstudded Oscars audience in hysterics with his impersonation of 'rapper' Joaquin Phoenix last night.

The actor wore a big straggly fake beard to present the the award for Best Cinematography alonside actress Natalie Portman.

And in a spoof of Joaquin's recent series of bizarre public appearances, since the Gladiator star 'quit acting' to pursue a career as a rapper, Ben looked aimlessly around as his co-presenter introduced the nominees.

Ben as Joaquin (left) and the real thing (right)

And the crowd roared with laughter as he told Natalie "I just wanna retire from being the funny guy", prompting her reply, "You look like you live in a Hasidic meth lab."

We will be following Ben's new career as a cinematographer with interest...

Check out Ben's Joaquin impression below: