Tribeca 2012: Jason Segel on His Passive-Aggressive Mountain Man Beard and Writing His Own Films (Video)

Every star in The Five-Year Reunion had to make some sort of change for the film. Alison Brie took on a British accent, Emily Blunt learned to speak like Cookie Monster, Chris Pratt cleaned up -- and Jason Segel did the exact opposite.

our editor recommends

Tribeca 2012: Emily Blunt Gives Her Cookie Monster Impression, Talks 'Five-Year Engagement' and 'Looper' (Video)

Tribeca 2012: Alison Brie Dishes on Her Amazing Elmo Impression and Drops a 'Community' Spoiler (Video)

As the romantic comedy's plot takes his character into a multi-year sojourn into the strange land of Ann Arbor, Michigan (hey, he's from San Francisco), he uses his free time to become a veritable outdoorsman, complete with hunting skills, horrible clothing and just about the most ridiculous beard possible.

Rocking some scruff of his own at the film's premiere at the Tribeca Film Festival on Wednesday night, Segel explained the origins behind his mighty movie mane.

"That was fake, but we call it the passive-aggressive facial hair," he told The Hollywood Reporter. "I think every guy has had a moment in their life where they grow weird facial (hair) to show that they don't care."

STORY: Nicholas Stoller Talks Embarrassing Jason Segel and Their Lunch Obsession 

Of course, that hair -- or any of the other embarrassing pratfalls that befell his character -- wasn't some unwanted part of the film's script that he couldn't get scrubbed; Segel co-wrote the film with director Nicholas Stoller. The pair have worked on three films together in which Segel has starred, and don't expect him to start writing for other people quite yet. He says he isn't at a place in his career that he can write for others, and by writing for himself, he gets to make himself a better actor, too.

"I'm very firmly aware of what I'm capable of and what my limits are so I try to write movies that stretch those limits a tiny bit so that I get better and better," he said.