During a guest appearance on Watch What Happens Live on Wednesday night, Seth Rogen, who is famous for playing stoner roles in films, revealed a list of celebrities that he has smoked marijuana with in the past.

"I'm going to go through a list of your co-stars and celebrity friends, you tell me if you've blazed up with them or not," said Andy Cohen in a segment called "Spill the Herbal Tea."

The 31-year-old actor named some well-known marijuana aficionados, including Snoop Dogg and Paul Rudd, however the shocking factor was when he spoke about his partner-in-crime, James Franco. "This is really depressing for me to say," he said. "I've never smoked weed with James Franco -- because he doesn't smoke weed."

"Oh my God! That's headline news!" the host shouted.

"That's why he's such a good actor!" Rogen added. "It's really sad, actually."

James' younger brother, actor Dave Franco also happened to be a guest on the evening's show. He admitted that the closest his brother had come was "secondhand smoke" from Seth Rogen.

When asked about Barbara Streisand, the "Knocked Up" actor, who revealed smoking with Sarah Silverman many times and Jonah Hill a few times, replied: "No, but we talked about it a lot. She smoked weed with Peter Sellars though. That's the craziest shit ever!"

"What about Willie Nelson?" Cohen asked of the country singer who is known for his heavy smoking habit. "No," Rogen said, wishing he could one day. "But he's here in town I think..."

The host then revealed he once shared a joint with Nelson himself. "By the way, it's crazy and I just realized it, I've smoked dope with Willie Nelson," he said. "It's amazing, it's crazy." He also recalled that it was at "a party at someone's house in New York" and the singer showed up and said, "Hey, I have this huge cigar-sized joint."

Impressed by Cohen's testimony, Seth Rogen said: "He's like 80 years old. I'd be afraid he'd start coughing and his whole insides would come out!"