Danny Zuko and Sandy Olsson were the perfect pair in Grease! The iconic movie tells the story about a high school couple who struggle to make their relationship work after they fall madly in love with one another over the summer. In the beloved film, Olivia Newton-John famously played good-girl Sandy and John Travolta portrayed Danny, a grease-loving bad boy.

This year, the film turns 40 and in honor of the anniversary, Grease star Didi Conn (aka Frenchy!) dished on some big behind-the-scenes secrets from the 1978 musical. In a new interview, Didi revealed that John was attracted to Olivia during the movie's shoot. "Oh yeah, [he did like her]. What was so much fun was that most of us were older than the characters we were playing so we just stayed in character all day long. So there was an ongoing improvisation happening so the flirting… was fine. It was the context of the characters and the storyline," she confessed.

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While speaking to the Daily Mail, Didi also revealed that the film's 40th anniversary edition includes an alternate ending for the movie where Danny gives Sandy a big kiss in the final car scene, as opposed to the original version where they only kiss at the beginning of the movie.

"So the beginning of the movie, Sandy and Danny are kissing and then she pulls away dramatically… [She's] sad and wondering if they'll ever see each other again," she explained. And, sadly, they don't kiss in the movie again — which prompted the director, Randal Kleiser to create the new alternate ending. "You see for a moment she’s surprised and then she responds. It's juicy and it's great. They weren’t acting at that moment, it was like he had his chance and he was going to take it. It was real, it really was," Didi gushed.

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Didi in 2016.

According to Didi, the hit musical was also supposed to have a sequel called Summer School which followed Danny and Sandy's romance after graduation. "John and Olivia said, 'Yes, we had such a good time let's make another one right away.' And Paramount said, 'I don’t think this is going to go anywhere. We're glad you all had a good time but no,'" Didi revealed. "Nobody knew, but we really had a wonderful time!"

The cast had so much fun shooting that the 66-year-old joked about having a cloudy memory at the Grease wrap party after her co-star Stockard Channing (who played Rizzo) made the cast "special brownies." Didi recalled, "I don’t remember much about the wrap party because Stockard Channing gave everybody some brownies she made. I really don’t remember much, just dancing, and lying on the floor, laughing with everybody."