With the hilarious mock biopic Walk Hard, John C. Reilly goes from supreme second banana to headliner. Having proven his mettle as a scene-stealing sidekick in everything from Boogie Nights to Talladega Nights, Reilly nails the lead role of Dewey Cox, a hysterical hodgepodge of Elvis, Johnny Cash and a half dozen other pop legends, who rides a rollercoaster of fame, drugs, sex and more drugs through a decades-long career of hits. Just before Walk Hard opened, Playboy.com caught up with Jake Kasdan, who co-wrote and directed the film, and then Reilly, to talk Cox, casting the role of a penis and pubic hair realism.

Playboy.com: In the film's orgy scene, there's a penis that plays a major role. Was there any audition process for that scene?

Jake Kasdan: It's not as easy as you would think to find somebody to do that. So we put out the word that we were looking for a guy to be full frontally nude. And there were a lot of volunteers. It's not hard to find people who are willing. What's hard is figuring out what you're getting exactly. So they send over this stack of Polaroids [laughs], and I went through them. There were just guys in their underwear, actually not naked. So you're just trying to guess and it's horrible. [Laughs] We were going through these pictures and finally, we got to one guy who was actually naked. He was just sort of staring into the camera with this goofy smile. There was something so funny about what he looked like and how unfazed he was that we auditioned him. We gave him the part, and he's hilarious. His name's Tyler Nelson.

Playboy.com: He has a speaking part, so he gets SAG credit.

Kasdan: Oh, yeah, absolutely. I think he deserves it. Character of Burt. We have a piece on the DVD that we call the "Cockumentary" about the penis scene. An interview with the penis.

Playboy.com: When you went into this movie, did you have a quota of how many times you used the word "Cox"?

Kasdan: It was more that we were all such children about it and we just couldn't stop. John embraced the Cox jokes so completely, so then it was the go-to move. Whenever anything was flagging, we would make sure there was a Cox joke. There are a couple scenes that are not in the movie that had five or six Cox jokes apiece. So actually, the movie has been de-Coxed.

Playboy.com: Was there anything specific John C. Reilly brought to the role that surprised you?

Kasdan: Early on, we came up with this idea that Dewey starts collecting exotic pets as a way of expressing his wealth and success. That's how decadence and luxury are portrayed on the rise to fame in the '50s -- he's got a monkey and a camel and a giraffe. He got very into that, and he had always wanted to do a scene with a chimpanzee. He felt strongly that we not change the kind of monkey. And he was right, it was better with the chimp. You can't have a spider monkey. It's not as funny!