Kieran Culkin was actually in Home Alone with his brother Macaulay and no one realised

Christmas time is fast approaching and that can only mean one thing... It's time to rewatch Home Alone again!

No matter how many times we've seen it, we always love to watch Macaulay Culkin wreck havoc against the Wet Bandits.

Nothing quite says festive spirit like a grown man screaming in pain as he steps on a nail or a shattered Christmas bauble, right?

But here's something to keep an eye out for on your 100,000th viewing of the 1990 classic - Macaulay's brother is in the movie too.

Kieran appeared in the film, but not in the role of a sibling as many might assume.

Instead, the pint-sized actor played Kevin McCallister's younger cousin. Yeah, that family had a lot of cousins to go around, but this one was particularly memorable.

He was Fuller, the kid who wet himself... You all remember him.

It's that scene where they're eating pizzas in the kitchen and you hear one of the adults chastise: "Fuller, go easy on the Pepsi!" Kieran, decked out in dungarees and glasses, gives the camera a cheeky grin.

Fuller McCallister loves drinking Pepsi... despite his bedwetting issue (20th Century Fox)

Overdoing it with the Pepsi might be the culprit behind the bed wetting problem, just a hunch.

Anyhow, it turns out that this scene actually helps set up the film's central premise.

See, Kevin was meant to be sharing a bed with Fuller the night before the big family holiday to Paris. But once Kevin protests that he doesn't want to share sleeping quarters with a bed wetter, his mum agrees to find Fuller an alternative bed.

Therefore, Kevin is up sleeping in the attic by himself and is forgotten the next morning in the rush for the airport.

Who knew that being a bedwetter would set up the plot to a holiday classic so nicely?

Hilariously, Kieran didn't really grasp the film's plot until he saw it in the cinemas.

Kieran Culkin admitted he didn't understand the film's plot at first (The Ellen DeGeneres Show)

Speaking to James Corden in 2020, he said: "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.

"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.'"

I'm not sure about you but I don't think there's much movie potential in the kid who got mistaken for Kevin and then went home.

Thankfully, we got the story about the kid who put a tarantula on a criminal's face.

Merry Christmas!