The "127 Hours" star was briefly romantically linked to the troubled actress, and earlier this year, he told shock jock Howard Stern he turned down a night of passion with Lohan when they were both staying at famous Los Angeles hotspot, Chateau Marmont.
Franco told the radio host, "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, in his riotous new comedy, in which Franco plays an exaggeration of himself, the actor reveals he slept with Lohan after she mistook him for Jake Gyllenhaal.
He says, "I told her to call me Prince of Persia" -- a reference to Gyllenhaal's 2010 movie flop "Prince of Persia: The Sands of Time."
The new film, in which Franco, Seth Rogen, Jonah Hill, Craig Robinson, Danny McBride and Jay Baruchel all play themselves, also features Rihanna, Emma Watson, Mindy Kaling and Channing Tatum, among others, and a stunning cameo from the Backstreet Boys.
In the movie, Franco and his pals face the apocalypse after a party at the actor's pretentious new Hollywood home.
Who or What hasn't Lohan slept with.
She started out at 10 or 11 ??
Wasn't the first person who turned her down,