After directing the raucous comedies “Road Trip,” “Old School” and “Starsky & Hutch,” Todd Phillips made “The Hangover,” which became the highest-grossing R-rated film of all time ($480 million worldwide) last summer. For his encore, he reteams with “Hangover” co-star and fellow ShoWest honoree Zach Galifianakis for the November Warner Bros. release “Due Date,” which also stars Robert Downey Jr.

THR: Would you say your movies have a common theme?

Phillips: They’re about holding on to your youth or putting off responsibility as long as possible. There’s a point in your life where you have to choose responsibility, and the characters are putting off that choice.

If movies are a barometer of a person’s psyche, does that mean you have been putting off that choice?

Oh, for sure. I’m definitely getting closer to that fork in the road, and I’m trying to push it back a little. But if you look at the films I’ve made, they age with me. They’re always about people in my peer group because it’s where my own tastes lie. It would be hard for me to make a movie like “Road Trip” today.

In “Road Trip,” “Old School” and “The Hangover,” you make on-screen cameos as a guy in a track suit and a curly black wig. Who is he?

That’s an alter ego, not a character. We call him Mr. Creepy. His real name is Barry. He also makes an appearance in “Due Date” where he ends up with Juliette Lewis, who’s back playing her character from “Old School.” It sounds complicated. It’s only understood by me and a few people around me.

What’s Barry’s backstory?

It gets revealed slowly through all the movies.

So, fifty years from now…

(laughs) Yeah, you’ll get a full, rounded picture of who this guy is.

Do you have any desire to direct a film that is not a comedy?

A director’s job is a purveyor of tone. It’s not that comedies are harder than drama or drama is harder than comedy. To me it’s about a story you want to tell, what gets you excited and what turns you on at the moment. A lot of it has to do with casting and who I get to work with. A lot of it has to do with the fact that I love going to work every day, laughing all day long and trying to make people like Zach Galifianakis laugh. As a movie fan, every (genre) interests me, and I’m sure I’ll do other things in the future. Right now, I’m having a stupid time doing comedies.

What are some of your fondest memories going to the theater?

I remember getting a guy to buy tickets for me and my friends to “Star 80.” I approached many 30-year-old men when I was 12 and asked them to buy me tickets to movies. Now I’ve turned into that man. There’s nothing I hate more than kids buying tickets to other movies and then sneaking in to an R-rated film. Then the wrong movie gets the receipt. So I’m happy to buy tickets for 12-year-olds and walk them in to the movie.

When was the last time you did that?

For “The Hangover,” I’d stand outside the AMC Citywalk and do that.

Have you ever walked out of a movie?

Sometimes I walk out of movies when I feel like they should end. It’s not that I think the movie’s bad. I just feel like, ‘Oh okay, they’re gonna go on for another 15 minutes. This will be a more pleasurable experience for me if the movie ended right here.’ I sort of choose my own ending and walk out. But that doesn’t mean I didn’t like the movie.