The 66-year-old actress is best known for playing Frenchy in the iconic musical movie - which starred John Travolta and Olivia Newton-John as romantic leads Danny Zuko and Sandy Olsson.
Didi still treasures the special memento from John, 64, but was surprised when she found out he had given the same gift to the other Pink Ladies, who were played by Stockard Channing, Jamie Donnelly and Dinah Manoff.
Speaking exclusively to BANG Showbiz, she said: ''John gave me a necklace, this is my good luck charm for whenever I do any kind of 'Grease' thing, it says JT and DC on a silver Tiffany heart with 'Grease the Musical' on the back, but he gave it to the other Pink Ladies too, I thought he only gave it to me!''
To celebrate the 40th anniversary of the film NOW TV recreated Frenchy's bedroom set from the movie where the Pink Ladies sing 'Look at Me, I'm Sandra Dee' as a pop-up in London and Didi is excited for people to have the opportunity to experience the same ''vibe'' the cast did on set.
She said: ''I thought it was brilliant, think about what came before the scene in the bedroom, poor Sandy she was so upset, and Frenchy says 'What you need is a night out with the girls,' so to make a party for people to come in and feel the vibe of happiness and fun and that camaraderie is great!''
Didi launched the NOW TV slumber screening pop-up earlier this week.
NOW TV subscribers can stream 'Grease' with a Sky Cinema pass for £9.99.
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