SETH ROGAN IS A MATURE ADULT (SORT OF) IN 'BAD NEIGHBOURS'

Seth Rogan and Rose Byrne in 'Bad Neighbours'. Credit: Universal Pictures.

Seth Rogan is the producer and star of 'Bad Neighbours', and in somewhat of a change for him, he plays an actual grown up with a job, house, wife and a new baby.

But as he and his wife are still adjusting to not being able to have all the fun they used to, a college fraternity takes over the house next door. Rogen and Byrne are pitted against the frat's young, charismatic leader - Zac Efron - over who is really in charge of their neighborhood.

For Rogen, who married actress Lauren Miller in 2011, his character's struggle is one he's seen his own contemporaries confront. In a phone conversation with Yahoo Movies, Rogen said, "This couple has a baby, and they're struggling with the fact that they can't party anymore and do all the fun stuff that they used to do. To me, that was something that I've seen happen with a lot of my friends. That's super relatable, and I really haven’t seen a lot of, if any, movies explicitly about that."

For his frat-boy nemesis, Rogen brought in a new face (and a perfectly sculpted one, at that), Efron. Rogen told us Efron actually agreed to star in the film before the script was even written just based on the pitch from writers Andrew J. Cohen and Brendan O'Brien (both of whom had worked on Judd Apatow films like 'The 40-Year-Old Virgin').

WATCH: 'Bad Neighbours' trailer

Rogen revealed that even though Efron was new to their heavily improvised style of comedy, he acquitted himself to it quickly. Rogen said, "He was really good at [improvising], and was really super funny in the movie, which is annoying, because he's super handsome too. I don't know how many points we've got to give this kid."

Rogen called out one spontaneous moment from a scene he and Efron had together that he truly wasn't expecting: "There's a scene where we're talking, where me and him were trying to bond, and we're talking about who Batman is to us. I'm talking about how to me Michael Keaton is Batman, and to him Christian Bale is Batman. And he whipped out this impression of Christian Bale as Batman that was really impressive. It's actually in the movie because it was so good. But again, I was like, 'F***, how many talents can one dude have?'"

Australian actress Rose Byrne was cast as Rogen's wife in 'Bad Neighbours', and while she first broke out as a dramatic actress, she has redefined herself as a comedienne in movies like 'Bridesmaids'. Rogen said they wanted a different take on the sort of male-female relationships you often seen in comedies.

He said, "We tried to approach the story the husband and wife a little differently than they currently generally do in these movies, in that we're really on the same team for a lot of it." Also, it's not just they guy coping with the demands of maturity. Rogen explained that Byrne's character "wants to have fun and is struggling with not being able to [do so] just as much if not more than I am in the movie."

The other new experience for Rogen in playing a father was working extensively with babies. But he said the twins who play his child in the movie were remarkably good-natured and cooperative.

Zac Efron and Seth Rogan star in 'Bad Neighbours', in cinemas from May 8, 2014. Credit: Universal Pictures.

"Even when there were 25 people in the room because of the crew and stuff like that, they're instinct was to look at me and Rose, which was really helpful," Rogen said. And since the babies were too young to talk, Rogen didn't really have to watch his language, "The babies were in some very explicit situations at times," Rogen recalled, "and they luckily had no f***ing clue what was going on."

Rogen revealed that there was a scene that required a bit of special consideration for the infant actors, and it's one that is featured in the trailer. "The baby eating the condom was maybe something that probably required a couple extra conversations," Rogen said, "but it all worked out in the end." The props department created a custom-made fake condom that would be edible and completely harmless to the youngsters. Rogen said, "I ate it myself just to be sure."

So maybe he's not grown up all the way quite yet.

Directed by Nick Stoller ('Forgetting Sarah Marshall', 'The Five-Year Engagement') and co-starring Dave Franco and Christopher Mintz-Plasse, 'Bad Neigbours' opens in Australian cinemas May 8, 2014.

Matt McDaniel writes for Yahoo! Movies