Want some fries with that murder?

The fragrance of fast food is all over “Scotland, Pa.,” the Roundabout Theatre Company’s riff on “Macbeth.” Like the quirky, 2001 film of the same title, the musical’s set in 1975 at a Pennsylvania burger joint where one couple’s dreams go way beyond their new deep fryer.

To immerse the audience in that greasy world, the Laura Pels Theatre’s lobby concession stand sells french fries — from Times Square’s the Counter — at intermission. Just as well, because one tends to work up an appetite watching the actors chow down.

“I like seeing people eat onstage,” says director Lonny Price, whose 2003 “’Master Harold’ . . . and the Boys” featured an onstage milkshake, ice cream soda and pea soup. “It’s human behavior, and we do it all the time. I certainly do!”

Granted, much of the food onstage isn’t what it appears to be. Jay Armstrong Johnson’s Banko consumes what looks like a piece of shrimp, a hot dog and a mini cherry pie at every performance. The shrimp is real, says Johnson, but the hot dog and pie, not so much.

“They graciously made me a turkey dog so I know what kind of meat is going into my body,” he tells The Post, “and the pie is really a granola bar, which is a lot less messy . . . It’s a three-course meal: appetizer, entrée and dessert!”

Even so, he says that he and the rest of the cast find themselves with a sudden craving for the real thing. “We even have some vegan-leaning cast members who’ve been trying meat lately,” he says.

Megan Lawrence isn’t one of them. Though she plays police detective Pat McDuff — a vegetarian forced at gunpoint to bite into a giant McScotland burger — in real life, she’ll take beef every time.

“If there’s not some kind of dead animal on my plate, I don’t think it’s a meal,” the mother of four tells The Post with a laugh. “But we went with a MorningStar Grillers veggie burger because it can sit out for hours without looking skeevy.”

One of her biggest challenges is biting into the McScotland burger: a supersized tower of two patties, three buns, lettuce and cheese. “Last night I took the biggest bite and then I couldn’t talk!” she says. “I kept chewing and spitting out food.”

Choking hazards aside, the actors say it’s fun to eat in a show, especially when they’ve hardly touched anything before getting to the theater. The only drawback?

“I’ve been eating more hamburgers than I ever have in my life,” says Price, their 60-year-old director. “And I’m sure it’s because of this damn show!”