(EW.com) -- The challenges involved in bringing "Men in Black 3" to the screen -- the ever changing script, the production delays, the budget that reportedly soared past $215 million -- are not exactly a secret.
If the thing had been a cakewalk, odds are we wouldn't be sitting here 10 full years after the last installment of the sci-fi-comedy series, gearing up for the new film's May 25 release. But co-star Josh Brolin had his own personal slice of misery to contend with in the making of "MiB3": honing his impression of Tommy Lee Jones. The film's storyline has Will Smith's Agent J traveling back in time to 1969 to prevent an alien baddie named Boris (played by Jemaine Clement) from assassinating Jones' Agent K -- and the critical job of playing that younger incarnation of K fell to Brolin.
"That was the toughest thing I'll ever do," Brolin tells EW. "I'm literally reliving it with you right now, and I'm so happy to be able to laugh about it."
Brolin had worked with Jones twice before -- in the 2007 films In the Valley of Elah and "No Country for Old Men" -- and gotten a chance to study the actor's very specific and sometimes, shall we say, prickly vibe up close.
"The ambiance that Tommy creates on a set is just unparalleled," Brolin says, laughing. "The tension is f***ing amazing. I just found it fascinating. I grew up with a lot of cowboys, so it doesn't affect me as deeply as it would the urban norm. I just laugh at it. But it's still uncomfortable. That's his genius: 'How can I make this the most uncomfortable moment anybody has ever had in the world?' There's no way he's thinking it -- it's just intrinsic."
From observing Jones, Brolin had developed a decent impression of the actor's deadpan, laconic, staccato way of speaking that, by chance, he shared with "Men in Black 3" director Barry Sonnenfeld one night at a dinner with the Coen brothers during the "No Country" shoot. It was good enough to convince Sonnenfeld that Brolin was the only choice to play the young Agent K. Still, Brolin wasn't initially convinced he quite fit the part: "It's like, 'Why me?' I don't know if it's the Americana people see in me and Tommy. Or if it's the size of our skulls. Or if there's a Cro-Magnon feeling when you look at us -- sort of a silverback thing."
Whatever their resemblance, the prospect of going from a casual impression of Jones to a full-fledged performance as young K was terrifying, Brolin says.
"I did lots and lots of practicing [in the months leading up to production]," he says. "I was just sitting there with Garage Band [recording myself] going, 'Hey, how ya doin'? Hey, how ya doin'?' --- over and over, for days and months, thinking, 'I'm going to sound like an idiot in this film.' I was down in Mexico at one point with a buddy of mine and I was so frustrated, I got so drunk -- the stress level was just so high. I never felt like I had it, and I still don't."
By all accounts (and judging from the movie's trailer), Brolin nailed the performance, much as he did with his well-received turn as George W. Bush in Oliver Stone's "W."
"You don't want it to be showboat-y," Brolin says. "The hope is after five minutes everyone will forget they're watching me doing Tommy playing K and just kind of lend themselves to the story."
But what was Jones' own take on Brolin's performance? Brolin isn't quite sure. "I didn't ever do Tommy in front of Tommy," he says.
"I know Tommy just saw the movie -- and his only comment was that he really liked [actor Michael Stuhlbarg's character] Griffin." He laughs. "Tommy's tough."
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