Kieran Culkin got a big surprise when he watched “Home Alone” for the first time! The 37-year-old actor and younger brother of Macaulay Culkin appeared in the beloved 1990 holiday classic as Fuller, the bed-wetting cousin of Macaulay’s character, Kevin McCallister. But when Kieran filmed the movie at the age of seven, he wasn’t really aware of the film’s plot.

“I didn’t even know what the movie was about when we were doing it, so it was a fresh, brand-new movie when I saw it,” he explained on Thursday’s “The Late Late Show With James Corden”.

Not only did he not know the plot of the film, Kieran didn’t even realize that his older brother was the star.

“There’s a part in the movie where there’s a kid who gets his head counted incorrectly and he goes, ‘Bye, bring me back something French!’ I thought the movie was about that kid,” the “Succession” star quipped. “And it made sense when I saw it. I remember seeing it in the theatre at the premiere and I was dying laughing and I was like, ‘Oh, that makes sense ’cause Mac was on set all the time.'”

Host Corden asked if the Culkin family can sit around and watch the iconic film like the rest of the world, and he had a surprising answer.

“Absolutely,” Kieran insisted. “Every Christmas that’s just on. I think we used to watch it a bunch even as a kid, so it just has that same sort of nostalgia.”

Kieran echoed this sentiment at the 2019 Golden Globes, telling ET, “You would think that because he was in it, because it was such a big thing, that we wouldn’t be able to enjoy it like a Christmas movie. But over the years we have been able to. Yeah, we watch it! I haven’t watched it in the last couple Christmases, sort of like “A Christmas Story”, I used to watch it every year and it’s like I need a break every couple years before I can watch this one again.”

Kieran added that Macaulay loves to make people feel old as evidenced by his recent 40th birthday post.

“He says that he’s really proud that he ages people. When he turned 30, people were like, ‘Oh my god, I’m old,’ so he loves telling people, ‘Hey everyone, I’m 40!'” Kieran quipped.

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