Princess Diana once revealed her favorite scene from an iconic film from 1989.

During her conversation with director Rob Reiner, the Princess of Wales revealed that she loved “When Harry Met Sally.” While speaking with Extra at the 30th anniversary of the movie, Reiner detailed his conversation with the late royal.

“We were all sitting there nervous because as we approached the famous scene in Katz’s Deli where my mother says, ‘I’ll have what she’s having.’ We realized, ‘Oh my God, I wonder how she’s gonna react to it?’” he said.

Upon hearing the iconic line from the movie, Princess Diana laughed. She also turned to actor Billy Crystal and said that she would be laughing a lot more but she knows that everyone was watching her.

Princess Diana had a great sense of humor when she was still alive. In the documentary “Diana, Our Mother: Her Life and Legacy,” Prince William recounted one of the late royal’s hilarious antics when he was still very young.

“She had a very cheeky sense of humor. She was a massive card writer and she loved the rudest cards you could imagine… I would be at school and I’d get a card from my mother… Usually, she found something you know, very embarrassing, very funny card, and then sort of written very nice stuff inside,” he said.

Prince William revealed that he didn’t open the card from his mother to hear that his teachers or classmates would see what’s inside the note. According to the future King, the Princess of Wales was very informal and she also really enjoyed the laughter and fun.

Prince Harry also talked about his mom’s wicked sense of humor and said that Princess Diana actually had a motto about it. When she was still alive, she used to tell her son that they can be as naughty as they want but they also have to make sure that they won’t be caught.

Princess Diana Britain’s Princess Diana arrives on Oct. 4, 1990 for a charity gala at the Departmental Auditorium in Washington. Photo: Kevin Larkin/AFP/Getty Images