Actor Robert Downey Jr has in the past been applauded for his edgy roles. But his latest may be a step too far - as the actor dons make-up to play a rather convincing looking black man in a new Hollywood film starring comic actor Ben Stiller. In a still from film Tropic Thunder, Downey Jnr is sandwiched between Ben Stiller, and a blonde Jack Black. Controversial: Actor Robert Downey Jr is virtually unrecognisble seen here sandwiched between actors Jack Black, left, and Ben Stiller, in an image from new film Tropic Thunder in which he wore a wig and...