In the upcoming "Men in Black 3," Agent J (Will Smith) travels back to the '60s, where he meets the younger version of his longtime partner Agent K (Tommy Lee Jones). For those of you who have seen the trailer, Josh Brolin does an ace job of imitating Jones' distinctive voice and stone-faced stare.

Actors get paid to pretend they're other people, but doing an imitation of someone you're friends with can be a bit trickier, as Brolin discovered.

it's been ten long years since "Men in Black 2" came out, and Brolin was keen to join the series and work with director Barry Sonnenfeld  Though he says he jumped on board immediately, Brolin admits that the situation didn't really hit him until he was on set. It then became a "working decision as opposed to a drunken bar fun decision," and he had to focus on capturing the spirit of K without stepping on Jones' toes. It was intimidating for him to be imitating someone he sees frequently in social circles.

Eventually, Brolin got to a point where he felt "comfortable where he [Jones] accepts what I did"

The experience also made Brolin see the previous films in a new light, noting that seeing K's transformation onscreen in the third film "makes me want to go back and watch the first one again."

Brolin also adds a big shout out to cast mate (and "Saturday Night Live" mainstay) Bill Hader, who plays a certain sixties fixture in the film. 

"Men in Black 3" opens nationwide May 25.