Ben StillerBen Stiller has said he was “blown away” by Robert Downey Jr on the set of their new film Tropic Thunder.

Ben told Playboy recently: “I started trying to copy him.

“It was like, ‘Wow, this guy’s a genius; maybe if I do what he does, I’ll be a genius too!’

“If he had spun around and thrown oat bran at the moon, I’d have run out, bought some oat bran and started spinning.

“I want to look like I’m as big a genius as he is.”

The comedy film, about a war film, opens in the US next month.