Ben Stiller (left) and Owen Wilson
Kevin Winter/Getty; Fame
They may be all laughs together on the silver screen, but when it comes to friend Owen Wilson
's attempted suicide last year
, Tropic Thunder
star Ben Stiller is gravely serious.
"I love Owen, and I felt bad that he had to deal with all the outside bulls--," the comic actor, 42, tells Playboy
in its August issue. "It's impossible to understand that kind of pain – depression or anything like that – until you're in it."
On a cheerier note, Stiller admits to idolizing costar Robert Downey Jr. on the Thunder
"Because I was so blown away by the guy, I started trying to copy him," he says. "It was like, Wow, this guy's a genius; maybe if I do what he does, I'll be a genius too!"
And as for leading-man Tom Cruise, who does an unflattering turn as a bald studio head in Tropic Thunder
, Stiller was impressed with his enthusiasm.
"The role was his idea," he says. "It wasn't even in the script. I didn't have to persuade him."