If you wrote Seth Rogen’s credentials down in a lonely hearts ad, he’d struggle to get a date. Despite his GSOH, with his big hair, ginger beard, thick glasses and spare tyre, he’s not exactly George Clooney. But since his star turn in Knocked Up, the surprise comedy hit of summer last year, this cuddly 26-year-old Canadian has emerged as Hollywood’s least likely romantic lead.

What’s more, he seems to have achieved it without undergoing an A-list personality bypass. Just a few minutes into an interview, he’s talking openly about pot smoking (“It’s basically legal in Vancouver”), making barbed comments about other stars, and debating such weighty issues as what to do if a bee gets into your car - rather than, for example, waxing lyrical about Pineapple Express, his latest film that has already become a cult hit (tagline: “They figured he was a lazy, time-wasting slacker. They were right.”) It was only when Rogen mysteriously wound up on the guest list for the Beckhams’ Los Angeles welcome party in 2007 that he finally realised he’d become a fully fledged movie star. “You know you’ve made it when you get invited to the David Beckham welcome party!” he says. “I didn’t go, though. I’ve never even seen him in real life. I thought that was weird - I’ve no idea how my name got on that list.”

Entertainment Weekly recently ranked him at number 20 in its “30 under 30” list of the hottest young stars, but Rogen insists his on-screen appeal has yet to translate into Beckham-level female adulation.

“My actual life has not changed,” he insists. “I look exactly the same on screen as I do in person. I don’t go through an Ugly Betty-type transformation. It’s not like I’m getting mobbed. I’m not Tom Cruise! Women aren’t exactly falling over themselves to get to me. On its busiest day, it occupies about three minutes of my life, literally, so I can’t qualify that as life-changing - it’s three-minute changing.”

Born to Jewish parents in Vancouver, Rogen’s father worked for nonprofit organisations, while his mother was a social worker. He spent his teenage years getting into minor scrapes, did “a lot of getting drunk in parks” and fine-tuned his natural comic skills on the stand-up circuit. He performed his first gig, aged 13, in Vancouver, in what he only later realised was a lesbian bar (he said later he thought it was ladies’ night).

“I’ve never had a normal job,” says Rogen, sounding like many of the drop-out characters he plays.

“I started doing stand-up when I was in high school, purely as a measure to never get a proper job. I’d be terrible at anything else. My grandfather owned a plumbing store that I maybe spent three days working in my entire life when I was like nine years old . . . actually it was probably more of a babysitting thing.”

At 16 he attended a casting call for Freaks and Geeks, a short-lived television series, where he met Judd Apatow, the director and producer, who became his mentor. This led to roles in Apatow projects including Anchorman and The 40 Year Old Virgin and culminated in his first starring role in Knocked Up, which Apatow wrote and directed.

Rogen has followed that success with Superbad and Drillbit Taylor, both of which he co-wrote. His success was rewarded recently when Amy Pascal, chairwoman of Sony Pictures, reportedly bought him a $104,000 (£60,000) petrol-electric Lexus LS 600h.

He suddenly finds himself among Hollywood’s elite group of bankable box-office comic stars: a short list that includes Ben Stiller, Will Ferrell and Adam Sandler. He’s full of praise for Sandler: “His comedy albums especially - those were the funniest things ever - so filthy and disgusting.” But he’s not so sure about Stiller.

“Whenever I see Ben Stiller without his shirt on, it irks me. Why is he in such good shape? That’s not funny. There’s nothing less funny than picturing a guy in the gym for 12 hours a day,” argues Rogen, whose own fitness regime has consisted, up to fairly recently, largely of burgers, french fries and hash browns.

He may have a lot in common with the sort of slacker characters he plays on screen but Rogen’s life is now a lot more conventional and for the past three years he’s been settled with Lauren Miller, a screenwriter.

He credits a truly terrible first date with bringing the two of them together. “We got into a very bad car accident,” he says. “A 16-year-old kid stole his parents’ car and slammed into us. My car was completely ruined but we were both okay. I think that’s why she liked me.”

Rogen is warming to the comedy potential of his car crash theme and decides it’s time to ponder one of life’s big questions. “I’d always wondered, ‘What would happen if a bee flew into my car?’,” he says, mock earnestly in his deep, booming voice.

“Then a few years ago I was driving in LA and a bee flew into my car. What did I do? I freaked out and crashed right into the car in front of me. So I now know the answer is, ‘I will handle it as badly as you could ever handle that situation.’ I literally went ‘Euhhhh!’ and crashed the car.” Sounds like a scene from one of his movies.

SETH ROGEN: MY LIFE IN CARS
GMC JIMMY Rogen started learning to drive when he was 16 in his mother’s 4x4
ACURA RL At 18, he bought this secondhand 1997 Acura, Honda’s luxury US offshoot
LEXUS LS 600H Rogen now drives this petrol-electric hybrid - a reported gift from the chairwoman of Sony Pictures

MY STUFF...
ON MY CD CHANGER Wu-Tang Clan’s Return of the Swarm, Vol 5 and Weezer’s latest, Weezer (The Red Album). I also like classic rock, especially Led Zeppelin

ON MY DVD PLAYER I’ve been watching Top Chef because I’m really into food - as you can probably deduce from my waistline. I also like Lost, which is probably the best series on TV

I WOULD NEVER THROW AWAY My collectibles: my hand-painted Japanese toys and my awesome comic book collection