Jason Schwartzman is Talia Shire's son, Francis Ford Coppola's nephew, and Nicolas Cage and Sofia Coppola's cousin. Yet while the rest of the Coppola family seems very focused and serious, Schwartzman comes across as something of a loon.

Just before meeting him for an interview, he adjourns to his hotel bedroom for a quick newspaper photo shoot and returns a few moments later with his arms wrapped around his makeup girl and the photographer -- a joke he set up to make it look like he's a ladies man. You can't help but laugh at his screwball sense of humor. He brightens up the room.

Schwartzman's biggest claim to fame is playing the lead role, Max Fisher, in Wes Anderson's already-classic "Rushmore." In his off hours, Schwartzman plays drums with his catchy Weezer-like pop band Phantom Planet, formed when he was just 14. (Their new CD comes out next month.)

The 21 year-old has now come to San Francisco to promote his newest film, a brain-dead -- but strangely, surprisingly funny -- teen comedy called Slackers" (not to be confused with Richard Linklater's 1991 cult groundbreaker "Slacker").

In "Slackers," Schwartzman plays Ethan, a nerdy college spaz who falls in love with Angela (James King) the cutest girl on campus and begins stalking her, building a shrine to her and making a doll out of her stray hairs. He catches three of the most ambitious cool jerks on campus cheating and blackmails them into helping him score with the girl, who runs in their circle of friends.

Today Schwartzman wears his jet black hair in a thick sheaf of bangs flopped over his forehead and sports a ratty but comfortable looking layered wardrobe.

He can barely sit still. He offers everyone cookies, curls up in a chair and begins picking at a loose thread on his shoe. Before long, he interrupts himself to borrow my pocketknife to sever the annoying distraction. ("Boom, Boom, Shelacky, Shelacky, Boom!" he says by way of thanks.)

San Francisco -- and the Coppola winery in Napa -- act as a kind of home base for the young actor. "I have a lot of fond memories here," he says, in a moment of lucidity. "It's one of the happiest places in the world for me to be. It's the headquarters where the family will always gather. It's where I got hooked up with the people who were casting 'Rushmore.'"

For his new film, Schwartzman expanded on the Max Fisher character to create a truly damaged soul who has no idea how to relate to people. To this end, he invented several hilarious bits of comic business to enhance the character.

One is Ethan's ever-present backpack, always looking lopsided and out of place. "When you run it kinda goes the opposite way, and I tried to take advantage of that," he says. "We put, like, Ritz Crackers in it. The guy's like, 'what do you want in the backpack?' And I was like, 'Ritz Crackers, a troll, peanuts, newspaper,' I just started naming weird s---. I was f---ing around. The next day, the bag's full of this stuff. I was just kidding! It was the ultimate frat hazing thing. 'Find me an Arizona map, circa 1968! Bring me the head of an ancient vampire bat!'" Schwartzman jokes.

In addition, Schwartzman shaved his chest hair into the shape of an "A" for Angela."

"What's that one thing that's just gonna throw it over the top and really drive home that I'm obsessed with her," he asks by way of explaining his motivation. "By this point -- it's three-quarters of the way (into the movie) -- we know I'm obsessed with her. We've seen the hair doll. We've seen the shrine. What's one more reveal that's going to take me from creep to freak? I mean, I've got it (he points at his voluminous chest hair) why not go for it?"

I tell Schwartzman that his performance reminded me of Jim Carrey's underrated turn in the 1996 film "The Cable Guy." He's genuinely pleased. "Thank you very much because that is one of the greatest movies ever made! It's genius! It's one of the only DVDs I own," He bellows out his best Jim Carrey impression: "CABLE GUY!!!"

With all this weirdness going on during the shoot, Schwartzman admits that he and his co-stars cut loose whenever possible. They would shoot two or three takes as written in the script, and then a few more just going nuts. "They could cut another movie from the outtakes. We shot a lot of stuff. I apologize to the financers about that. We wasted a lot of film. Because -- come on -- we can't take this seriously or we'll be the biggest idiots in the whole world."

Schwartzman says that actor Jason Segel (TV's "Freaks and Geeks") was his biggest nemesis in the giggle department. "I can't stop cracking up around that guy," he says. "He's unbeatably funny. Sometimes they'd have to cut because we'd just be talking and just looking at each other. I'd look in his eyes and I'd just start cracking up. I'd just see him laughing in his eyes and I'd lose it! 'Cause I'm a crackup. I'm not a very hard man to make laugh."

For all his natural loopiness, Schwartzman has stayed busy and has at least two more high-profile movies coming out. The first is S1m0ne," starring Al Pacino and directed by Andrew Niccol, the celebrated screenwriter of The Truman Show and the writer/director of Gattaca. "That's gonna be good," he says. "That's all Al's movie. I'm seriously in the background. I have like four scenes. It was just a chance to watch him work. 'Cause for every minute of screen time, there's six hours of waiting around. I almost play a mute. I'm a reporter. I just stand in the back and take notes."

Schwartzman will also star in Spun," a half-animated, half-live action film by director Jonas Akerlund. "I didn't know what he was going to do. I remember telling the director one time, 'I feel weird about that one scene. I don't think I nailed it.' And he goes, 'don't worry, we're going to be on a cartoon fly on the wall.' I was like, 'Okay, I'm in over my head. I have no idea what we're shooting anymore. See you at the premiere.'"

Besides acting and playing drums, Schwartzman hopes to increase his repertoire. "Every actor I ever meet goes, 'Ultimately I plan on having my own company and write and direct.' Yes, I too would love to write and direct a movie. I want to do a play, too. I want to do it all." He deadpans, "I'm competing in the Winter Olympics. My plate is full."