"To be honest, he played a black dude better than anybody I've seen," Downey's African-American "Tropic Thunder" co-star Brandon T. Jackson told People.com. "When I first read the script, I was like: What? Black face? But when I saw (Downey act) he, like, became a black man."
Directed by Ben Stiller and co-starring Jack Black, the big-screen comedy features Downey as an Oscar-winning actor who takes on a role in the most expensive Vietnam war movie in cinematic history, then dyes his skin when he hears his character was originally written as an African-American.
"It was just good acting," Jackson told People.com. "It was weird on the set because he would keep going with the character. He's a Method actor."
Downey also starred in the recent blockbuster "Iron Man."