Mila Kunis thought that renting an RV and hitting the road with husband Ashton Kutcher and their 10-month-old baby would be the perfect way to spend their honeymoon.

It was not.

Promoting hew new big-screen comedy “The Spy Who Dumped Me” on “The Tonight Show Starring Jimmy Fallon”, she related the hilarious story of how her plans for an idyllic road trip with her new husband turned into a disaster-filled nightmare inside a “rented tin can.”

“If you’ve ever seen the ‘National Lampoon’ movies, our honeymoon was like a real-life ‘National Lampoon’s Honeymoon’,” Kunis explained to Fallon.

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According to Kunis, the trip saw the couple (who were travelling with Kutcher’s parents) experience one disaster after another, starting when the air conditioning in the RV stopped working a few hours into the trip — on a day when temperatures topped 43 degrees Celsius.

Things got even worse when Apple Maps sent them onto a fire road instead of a paved highway. “We all had to jump out of the vehicle and walk for, like, three miles while my father-in-law drove the van,” she told Fallon. “And Ashton, like, navigated him over gigantic boulders ’cause there had just been a massive flood.”

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According to Kunis, a mix-up in the itinerary (planned by her mother-in-law) saw them veer from their planned trip of Napa to Lodi — right near two prisons.

“My husband looks at me and goes, ‘Um, I quit.’ And I was like, ‘Me too,’” she recalled.

Later in the show, Kunis joined Fallon, fellow guest Zachary Quinto and Tariq “Black Thought” Trotter for a game of “Say That to My Face” — watch:

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