• Nick Kroll and Andrew Rannells play a married couple whose vacation to Italy goes hilariously wrong in I Don’t Understand You
• “I really did rely on Nick, and I leaned on Nick. He was very generous, and we really took turns taking care of each other,” Rannells tells PEOPLE
• I Don’t Understand You, which also stars Amanda Seyfried, is in theaters June 6

Big Mouth fans have enjoyed Nick Kroll and Andrew Rannells cracking jokes on Netflix for years, but the pair brought laughs and a whole lot more to their new dark comedy I Don’t Understand You.

Kroll and Rannells, both 46, play a married couple whose trip to Italy to celebrate an anniversary and their upcoming adoption of a baby goes terribly wrong. They get lost in a rural area on their way to dinner, and with no cell service and a poor understanding of Italian, their characters Dom and Cole resolve to defend each other when they encounter seemingly sketchy strangers after getting lost — and matters turn deadly.

“Obviously it’s very helpful that we were friends walking into it,” Rannells tells PEOPLE.

“The first things we shot were all of the fun touristy things that we got to do, like eating gelato and walking down the streets to Rome and seeing the Spanish steps. That was all really fun and cute. After a week of that, we then got into about a month of night shoots, and we were an hour outside of Rome in this farmhouse. It did just sort of become— I mean, we didn’t kill anyone!”

“Allegedly,” Kroll jokes.

“It was hard at times,” Rannells says. “I really did rely on Nick, and I leaned on Nick. He was very generous, and we really took turns taking care of each other. I really didn’t think too much about, like, how do we pull off being a couple.” Adds Kroll, “It was very natural, just very natural.”

Nick Kroll and Andrew Rannells in I Don’t Understand You. | Vertical

Kroll and Rannells’ new movie is based on the real-life experiences of writer-director duo Brian Crano and David Joseph Craig, a married couple who found inspiration for the film after they got stuck on the side of the road in Italy while celebrating their 10th anniversary, just before welcoming their first child.

Craig tells PEOPLE they cast Kroll and Rannells in these roles because the actors “love each other in real life and they really get each other.”

Plus, they had experience acting as part of a duo, between Rannells’ famous Broadway role in The Book of Mormon and Kroll’s years of comedy with close friend John Mulaney. “We couldn’t have asked for a better pairing of actors to be in these roles,” Craig says. (PEOPLE has an exclusive clip from the film showing off their onscreen dynamic, above.)

Kroll, who shares two kids with wife Lily Kwong, says the opportunity to work closer with his Big Mouth costar Rannells “was one of the main things that attracted me to doing this film.” The movie doubles as a parenting origin story and comedic vacation-gone-wrong nightmare that debuts as Pride Month begins and Father’s Day approaches.

“To have a film in theaters with gay characters in it is so unusual, and then to have them not be tragic characters or victims is also a real unusual thing,” co-director Crano says. “It just feels like a huge win.”

I Don’t Understand You is in theaters June 6.