"We're on the run, we don't have the chance to change, I have one outfit, so we'd better get it right," says Franco. "They wanted me to wear these Guatemalan pants. I was like, 'Who wears these awful things?' And Judd and Shauna Robertson, the other producer, are good friends with Woody Harrelson and said, 'Woody wears these all the time.' I even met some other friends of Woody's and they're like, 'Yeah, Woody wears them.' That's how the outfit came about."
He watched all the major stoner movies, including his favorites that "had something more going on" than just endless weed jokes, such as The Big Lebowski, Fast Times and Brad Pitt's stoned turn in True Romance. But he says he didn't actually smoke any illegal substances to get into character.
During interviews for Pineapple, he gets asked one question repeatedly: How did he and Rogen research their roles? So he has come up with an answer to throw interviewers for a loop. He tells them he experimented with black-tar heroin, but knew when to pull back.
That's his goofy, sharp sense of humor, also on display in his acting tutorials on FunnyOrDie.com.
"Basically, Pineapple is a documentary," he deadpans. "I was always going to play Saul. They found me in my apartment, there was no script, they just came into my place. My dealer came after me. It was perfect."
In reality, Franco says, "I used to smoke weed, but I haven't done it in a long time. Everybody, even now, thinks, 'That guy is stoned.' It's just the way I talk, because I don't smoke weed. Somehow, there's something about me, the way I talk, that implies that I'm on drugs."
Franco calls Pineapple the most fun movie he ever has worked on. He even had a Saul-like moment when he and a friend took his two plus-sized cats for a walk in Los Angeles.
"We got them leashes so we could take them outside, because they're completely indoor cats. They got so scared," says Franco. "We're walking down Sunset and one of them got out of the leash and jumped over the fence to the Chateau Marmont. We were hunting him down in the bushes of the Chateau Marmont."
The real Franco is nothing like Saul, who hides in trash bins, adores his Bubby (grandma) and slushies, and tries to smash a windshield with his foot.
"He's a very education-minded person," says Apatow. "We used to laugh because in between takes he'd be reading The Iliad on set. We still haven't read The Iliad. It was a very difficult book. With him, it was always James Joyce or something."
On the set of Freaks, recalls Franco, "this sounds so pretentious, but I was reading Proust. And Judd is like, 'Why do you read things like that?' I don't know. It's good? But Judd reads. He gave me a great book called A Fan's Notes by a guy named Frederick Exley."
Franco is showcasing his cerebral side in November's Milk, Van Sant's pedigreed political biopic starring Penn as gay activist Harvey Milk, the "mayor of Castro Street," who was assassinated in 1978. Milk producer Dan Jinks says Franco was cast because "there's a sensitivity that exudes from him. He can, without trying, make you see into his soul. He makes it seem effortless."