UK Version here... featuring the alternative title they're using in some places, 'Bad Neighbours'
ETA: Forgot to add the stuff Seth said in the interview that went along with this:
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").
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?'"