Details: Zach Galifianakis and Robert Downey Jr. have great chemistry in Due Date. What was their first meeting like?
Todd Philips: We went to Downey's house to have dinner. For some reason, Zach rode his bike. So he arrives 15 minutes late, sweaty, vile, and immediately puts his foot in his mouth by talking about an actress Robert used to date. I laughed, and Zach said, "You know what? I think I'm just going to go now."

Details: Between The Hangover and now Due Date, you've done quite a bit for that guy's career.
Todd Philips: Zach read for Tom Green's part in Road Trip, so I've known him for 10 years. I always knew he was supremely talented, but I never had the right part for him. People tell me that The Hangover was the first time Zach was used right. That's exciting as a director.

Details: The rumor is that you wanted to shoot him with a real taser.
Todd Philips: Yeah. We had a stunt guy do it, and then we showed Zach the tape. He almost vomited.

Details: There's a masturbating dog in Due Date. How do you get him to, you know, do that?
Todd Philips: You just hold a really hot poodle in front of him and hope nature takes its course. [Laughs] It took a little while. What you don't see is even funnier than what you do see: three ASPCA people hovering around and an animal trainer who, for some reason, has taught him to do that by saying "Get the carrot." Which I don't even understand, because he's not holding a carrot in front of him or anything. But he's going, "Come on, boy, get the carrot! Get the carrot!" That became a catchphrase for Due Date. We wanted to put it on the poster: Due Date: Get the Carrot.

Details: You have cameos in some of your comedies, but your appearance in Due Date is a little bigger. Are you trying to expand the character a bit?
Todd Philips: It's a little bigger, yeah, but it's the same character. It's this guy Barry, who is also known as Mr. Creepy, who is just the most sexual guy in all of my movies. He's back with Heidi, Juliette Lewis' character in Old School. She now has two kids. Are they Will Ferrell's kids? They might be. I don't know. [Laughs] We'll have to wait and see. That scene just created itself in a weird way. I just show up on the set—I'm usually high first thing in the morning—and we just kind of figure it out.

Details: Where did you get the idea to film a scene at the Waffle House?
Todd Philips: I just remember from shooting Road Trip that there are Waffle Houses at every exit, sometimes across the street from each other. So you try to add a layer of reality to the film. There's a scene in Road Trip where Horatio Sanz does something to the French toast. That was supposed to be in a Waffle House, but the CEO killed it because he didn't want to show that their cooks fuck with the food. Because they don't do that, obviously. [Laughs] So we went back to them with this idea for Due Date and they said yes. The CEO came down to the shoot and introduced himself. He said, "You know, I gotta tell you. When Todd Phillips wanted to come again to the Waffle House, I was really hesitant. I'm glad we dodged the bullet. This one's so much better."

Details: The Hangover is the highest-grossing R-rated comedy of all time. How do you pull off a worthy sequel?
Todd Philips: I'm not delusional. I'm aware that other comedy sequels have disappointed. So the first step was to call it The Hangover: Part II. Like The Godfather: Part II. That might be the only way a sequel holds up. When I typed the cover page, I was like, "There! Got that covered."

Details: Mike Tyson recently said he did his part in The Hangover for drug money. Did that upset you?
Todd Philips: I love that quote! But I didn't really understand the logic behind it. He said he wanted to bootleg the DVD but then it became an international hit. You'd think he'd make more money bootlegging it in that case. He was like [doing a Tyson impression], "I saw it on Canal Street, and I thought, 'We's trumped!'"

Details: Will he be in the sequel?
Todd Philips: Yes, he will be back. But it all makes sense. It sounds like a crazy hodgepodge, but it all makes sense.

Details: You're planning a John Belushi project. Does it worry you that the last Belushi biopic, Wired, bombed?
Todd Philips: That movie didn't seem to be about Belushi. Belushi is the funniest guy ever; that movie wasn't funny. His spirit was irreverent, something I love and revel in myself. We want to make sure the film respects that.

Details: Have you given any thought to who will play Belushi?
Todd Philips: We really haven't. Once we have it on its feet, we'll look at it and decide whether to get an unknown person so it's not colored or maybe get so-and-so. But that we're not close to.

Details: The popular Internet choice is Seth Rogen.
Todd Philips: Oh really? They want Seth Rogen. That's interesting. I honestly never even thought of that. Zach, obviously. I've thought of Zach because it's Zach, and I think of him for everything.

Details: Has your tremendous success in the past few years given you new perspective on your occasional failure?
Todd Philips: Absolutely. There's a saying that didn't come from Hollywood—that someone just made up—that goes, "You're only as good as your last movie." I don't subscribe to that. You're only as good as your body of work, and everybody has issues, whether it's Steven Spielberg or Martin Scorsese. I'm not comparing myself to those guys, but you learn more from the misses than the hits. It's not like you sit on the set of other guys' movies and learn that way. So one way to learn is to have a miss like School for Scoundrels and say, "Okay, now I can look back and dissect why that didn't work."