MONTREAL - Seth Rogen says his experiences smoking dope as a kid came in handy when he played a stoner on the run in his new movie "Pineapple Express."

He says it also didn't hurt that he grew up in British Columbia, known far and wide for its prolific marijuana production.

"I'm from Vancouver, which I guess is research in and of itself," the 26-year-old joked before the premiere of the movie at the Just For Laughs Festival, which wrapped up Sunday.

"I smoked a lot of weed growing up and that was kind of one of the funny things about this movie in that we had never really seen a movie that dealt with our kind of everyday weed experience."

In "Pineapple Express," which is named for a type of marijuana, Rogen plays Dale Denton, a schlub of a process server who fires doobies through his mouth like a machine gun fires bullets.

He has to go on the run with his dealer (James Franco) when he witnesses a murder committed by other dealers. Hilarity ensues.

"Clearly, I've never been chased by murderers," says Rogen, who co-wrote the film with Evan Goldberg and producer Judd Apatow.

"But when we were developing the relationship between the guys, it did come off our experiences, the kind of awkward interactions we've had with people we've bought weed from and just kind of ways we'd gone about our lives in the past," he said.

"It was definitely based on a lot of experiences that we had and that's why we thought it could be a relatable movie. We've been through this. Everyone's been with someone who's bought weed or knows someone who's sold weed or gone and bought weed themselves."

Co-star Danny McBride, who plays Red, the hapless middleman between Denton's dealer and a muderous drug lord played by Gary Cole, adds the buddy aspect anchors the film.

"Even if you don't smoke weed, I think you could still appreciate the film because the fact of the matter is it's about buddies, it's not necessarily just about weed.

"I think that's the thing that separates this from a lot of other stoner films. Those other films tend to be just about marijuana, the marijuana culture, and this to me just seems like it's a component of the film but not necessarily what the film revolves around."

Rogen has honed his portrayal of stoners in his last three films with producer-director-writer Judd Apatow, who also helmed "Pineapple Express."

The Los Angeles-based Rogen, who has a rep for playing average joes and losers, played the stoner buddy in "The 40-Year-Old Virgin," the stoner dad in "Knocked Up" and the stoner cop in "Superbad."

Besides appearances in this October's "Zack and Miri Make a Porno" from director Kevin Smith, he'll headline as a standup comedian in Apatow's next film "Funny People" and is set to star as a crime-busting superhero in "The Green Hornet."

"Pineapple Express" will probably provide valuable experience for that role, which had the beefy Rogen involved in a lot of hair-raising action.

"I hurt my finger pretty bad," Rogen reported of the aftermath of one particularly rollicking scene.

Apatow said that anyone who has seen any of his other efforts with Rogen won't be disappointed with "Pineapple Express," which opens on Aug. 8, joking there's not a lot of difference between it and the other comedies.

"Hopefully if we can get two per cent of the people who saw the midnight show of "Batman" we'll be happy," he said.

Tracking firm Media By Numbers said Friday that the latest Batman film, "The Dark Knight," set a box office record by bringing in $18.5 million in its midnight debut. It has also set an opening weekend record of $155.34 million.

Rogen, who was a standup comedian before he devoted his time to acting, returned to joke-slinging in a show at Just For Laughs. He said it went pretty well considering he hadn't done standup in around 10 years.

"It was a lot of fun," he said. "There were a lot of people, I think it was the most people I've ever performed in front of."

He joked he had only done one standup bit a few days before to prepare.

"But I was thinking what I've lost in skill I've made up in recognition so for the first 10 minutes, they'll laugh at anything I say anyway. I only did 12 minutes so I only really need two minutes of funny jokes. I just kind of coasted.

"And I'm from Canada, so that added those two minutes so I didn't have to say a thing."