Kieran Culkin Explains Why He Had 'No Idea' What “Home Alone” Was About When He Made the Movie with Brother Macaulay

"Drink this Coke, wear the glasses, say the thing that you memorized, look cute and go home," Kieran Culkin recalled of filming 'Home Alone'

Home Alone is now considered a holiday classic, but when the film first came out in 1990, one of its stars Kieran Culkin didn't fully grasp its plot.

"I had no idea what that movie was about when I saw it, and I was in it,” Culkin, 42, told the Los Angeles Times in an article published Tuesday, Dec. 3, as he and his A Real Pain costar and director Jesse Eisenberg promoted their new comedy-drama.

“I was at the premiere, and I was dying laughing. It was the funniest thing I had ever seen," Culkin added of watching the family comedy for the first time. "I had no idea what the movie was about.”

Culkin's brother Macaulay shot to fame as the star of Home Alone, Kevin McAllister. As a young child, Kieran portrayed Kevin's cousin Fuller. When Eisenberg, 41, asked Kieran how he could have made it through Home Alone's shoot without anybody explaining the movie's storyline, the Succession actor answered, "Drink this Coke, wear the glasses, say the thing that you memorized, look cute and go home."

Related: Kieran Culkin Didn’t Realize Acting Was His Passion Until 'Halfway Through the First Season' of Succession

“Devin Ratray, the guy who plays Buzz, lied to me and told me the movie was all about him," he added. "And I believed him. And then when I saw it, the movie’s cracking me up, and I go, ‘Mac was on set all the time. That makes sense the movie would be about him.’ ”

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In A Real Pain, Eisenberg and Culkin portray American cousins who travel to Poland together following their grandmother's death. While the two did not know each other well prior to making the movie, Eisenberg recalled that he saw Home Alone in theaters 17 times back in the 1990s.

Related: Home Alone House Owners Recall Finding Out Macaulay Culkin Cut Down a Real Tree from Their Backyard (Exclusive)

“I kind of knew the phenomenon of Kieran actually being the brother of the other guy,” Eisenberg told the L.A. Times. “I guess I knew that in some roundabout way. But I was not reading, you know, the trades."

Kieran recalled similar stories about making Home Alone when he and Eisenberg took part in a Tribeca Film Festival panel in June. "I have seen that movie so many times," he added at that time. "I grew up watching it over and over again on Christmas so I got that whole thing memorized."

A Real Pain is in theaters now.