"We'll rehearse and do improv before we shoot, and sometimes that kind of stuff makes its way into the script," he said. "But they both [Apatow and McKay] tend to shoot a lot of film in hopes of capturing some moment. And it's fun, it's a really fun collaborative, exciting way of making a movie.
"It is fun, I always hear that if you're working on a comedy and you're having a good time and laughing, that that just means the comedy is not going to work. The experience had to be grueling for it to work. I don't buy that at all."
And so, the classically trained actor has become a fixture in what some call Frat Pack films -- huge moneymakers, such as "The 40-Year-Old Virgin," "Forgetting Sarah Marshall," and "Role Models," which he co-wrote.
Mainly male-themed comedies about men bonding, though nothing quite as overtly about male friendships as his new movie.
According to the movie, the sacred fount of male bonding is music. Peter and Sydney spend the majority of their time jamming to the 1970s metal band Rush. Not a far stretch for Rudd, who said he used to DJ bar mitzvahs when he first came to Hollywood.
"On weekends, I got to go to school during the week and then do the horror on Saturday," Rudd said. "It's a tricky thing because you want to appeal to a 13-year-old and their musical taste, their party. ... This was in the early '90s, so, you know, at that time, it was M.C. Hammer or you don't want to play too much. ... The Commodores' 'Brick House' would still work on occasion, but 'Celebration,' that's always, that's a staple."
Rudd said he doesn't feel torn between acting in comedies and his past work in drama.
"I think most of these comedies could be dramas," Rudd said. "Honestly, the stories, the actual story, could be. They're character-driven. It's not about bad language or crude humor. That stuff is in it in a way to make the dramatic story a little bit more relatable. ...
"You want to be moved. That's no different than watching, going into a movie. You want to laugh, too, but it's nice if you actually care about the people you're watching."
"Nah, you know what, they're just comedies. Who am I kidding?"