He may have tried to seduce a 17-year-old via Instagram, but James Franco absolutely insists that he didn't do the nasty with Lindsay Lohan.

Franco appeared on Howard Stern's Sirius XM radio show on Wednesday, and though he admits to making out with the actress, he swears "on my mother's life" he never had sex with Lohan. "Alright, we maybe kissed," he said, but added that "it was lame."

Apparently the smooch happened in New York in 2004 when he was doing Spider-Man 2, and at the time Lilo was just a teenager. Hey, we know he likes 'em young! Franco said that at the time he asked himself, "What the hell am I doing?" Still, Franco says Lohan is "so delusional," adding, "I bet you if we brought her in here and you asked her to her face, 'Did you have sex with James?' She would say yes." Burn!

Franco went on to suggest that the 27-year-old starlet is obsessed with him, noting that when he was staying at the Chateau Marmont several years later she would stalk him. "I'd come home late to the hotel and she'd come find me," he said. "She even broke into my room one time ... I opened my eyes and there's Lindsay in my room at 3 a.m." Um, WHAT?!

Stern quipped that maybe her infamous sex list was simply just people she was once in love with, to which Franco replied, "Maybe that's why I'm on the list of her obsessions."

A year ago he chatted with Stern and revealed that he had turned Lindsay down when she made a pass at him, so his story seems to add up. "I don't want to brag about it. I don't know how that got out," he said at the time. "She was having issues even then, so you feel weird. Honestly, she was a friend. I've met a lot of people that are troubled and sometimes you don't want to do that."

But he's reeeeeally going out of his way to make sure we know there was no intercourse! Do you believe him?