Skyler Gisondo and Steele Stebbins play brothers in Vacation, a comedy-adventure film in which a family called the Griswolds goes on a trip to a theme park known as Walley World.

If that sounds a bit familiar, it’s probably because Vacation (now playing) is a sort of sequel to National Lampoon’s Vacation, in which Chevy Chase, in the paternal role of Clark Griswold, takes his family on that same fateful trip.

The latest version has Clark’s son, Rusty (Ed Helms), making the trek with his wife (Christina Applegate) and two kids (Gisondo and Stebbins). The offspring apparently didn’t get the history lesson, though. When the two young actors call the Straight from Los Angeles, they seem oblivious as to Vacation’s origins.

“There’s an original?” asks Gisondo.

“There’s seriously an original Vacation?” echoes Stebbins, his high voice piercing through the receiver. “I’ve never heard of that.”

Whether they are just kidding around or are actually unaware of the Griswolds’ first exploration is unclear—the two spend a good amount of the interview making inside jokes to each other—and it also doesn’t really matter.

There was more than a decade between the release of the original movie in 1983 and the birth of Gisondo, the older of the two at 19. And while Chevy Chase does show up as Grandpa Clark, this is clearly a new era, with two young stars ushering it in by playing against type. Gisondo’s James is a nerd, while Stebbins’s Kevin is a jerk to his older brother.

“The funny thing is that we’re actually very far from our characters. I play an excruciatingly awkward kid who keeps a stack of journals a foot high. And in real life, I’m just crushing it,” says Gisondo. And yes, he’s kidding, he’s not actually that cocky. We think. “And Steele is, like, the nicest dude in the world in real life and in this he’s just so mean. And it just came very naturally. I definitely find myself going into James mode and being super weird around people.”

There was also the audition process, which took months for the younger actors and was held back even further when the film was delayed. “When I got the call, I was 15,” says Gisondo, “and they shelved it. And then, like, two years later it came around again. So it was a long time. Auditioned eight times. Chemistry reads with Steele, a lot of improv. It was fun, man. It was fun but long.”

“Before they shelved it, my mom was like, ‘You can do this, you’ve got this one,’ ” adds Stebbins. “She called that I was gonna get it before I did the first audition. When I got the call that I got it, I was actually on a cruise.”

“That’s the dream, that’s the dream,” says Gisondo.