Patrick Dempsey Being Crowned SMA 'Is Like Pouring Gasoline on the McDreamy Fire,' Jokes Eli Roth (Exclusive)

Eli Roth's latest movie stars the Sexiest Man Alive.

Filmmaker Roth, 51, recently spoke with PEOPLE about his new movie Thanksgiving, a holiday-themed slasher that features Patrick Dempsey as a Plymouth, Massachusetts sheriff dealing with a score of Thanksgiving-themed murders that take place as the town's residents prepare to celebrate the holiday.

"I think he just finally put McDreamy to bed, but now this is is like pouring gasoline on the McDreamy fire," Roth tells PEOPLE, joking about Dempsey's longtime role as Dr. Derek "McDreamy" Shepherd in the television series Grey's Anatomy.

"I think Patrick is in an interesting place in his career," the director adds. "He is in that Paul Newman moment where he is doing Thanksgiving, he's doing Ferrari. He's such an interesting actor and can kind of do whatever he wants."

Roth did not know Dempsey would be crowned PEOPLE's Sexiest Man Alive until his title was unveiled last Tuesday on Jimmy Kimmel Live!. Even so, the filmmaker is excited to playfully rib Dempsey over the reveal.

"Anytime he sits in a chair, it'll be the sexiest chair on set. If he uses a fork, it will be the sexiest fork," Roth jokes. "I can just add the word sexiest to everything, but Patrick, one thing I love about him — he's so down to earth. He has such a good sense of humor. He's the first one to make jokes about it, and the truth is that is what makes him so sexy."

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Dempsey's role in Thanksgiving is decidedly un-sexy. His character Sheriff Newlon is tasked with leading an investigation into a serial killer dressed up as a Pilgrim who begins terrorizing Plymouth's citizens and posting his murders on social media under the alias John Carver, the first governor of the 17th-century British colony in Plymouth where the first Thanksgiving was held.

"Every Boston movie is about some kind of criminal syndicate or fixture man or blue collar worker, and I just wanted to see Massholes in a slasher film," Roth says of Thanksgiving, which he says has been on his mind since he was a kid growing up in Massachusetts.

The film initially debuted as a faux trailer Roth and cowriter Jeff Rendell created that ran in theaters during the 2007 Robert Rodriguez-Quentin Tarantino double feature Grindhouse. They spent the intervening years developing it into a feature-length project.

True to Roth's Boston-area roots, the filmmaker found authentic New England accents among the slasher's cast members, including in Lewiston, Maine native Dempsey.

"When he reached out to he me said, 'Do you want me to have a light New England accent?' And I said, 'Well, I'm from there, so don't do the accent unless you really can do it,' " Roth recalls of Dempsey's assertion that he could put on his childhood accent for the film. "He goes, 'No, I grew up with it. This is my real accent.' "

"The accent in the movie is the accent that Patrick Dempsey grew up with," Roth adds. "He had to lose it for [the 1987 teen comedy] Can't Buy Me Love and for his acting career. But when you talk to Patrick, he's got a little bit of a light New England accent like that. It's pretty wicked."

Thanksgiving slashes into theaters Friday.