John Travolta and Olivia Newton-John donned their Grease outfits for the first time in 4 decades

The duo - who played Danny Zuko and Sandy Olsson - got dressed up in their famous outfits from the show for a special 'Meet 'N Grease' movie sing-along event in West Palm Beach, Florida on Friday (Dec 13).

Olivia excitedly wrote on her own Instagram page: "First time in costume since we made the movie! So excited!!"

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Meanwhile, John shared on his account: "#Grease is still the word. Opening night of #MeetNGrease at the @coralskyamp in West Palm Beach!"

Olivia previously admitted she has a unique bond with John.

She explained: "We did something life-changing, making that film. [At the premiere] you got the feeling from the energy that something was happening. It was a huge response. I feel grateful to be a part of that and to have worked with him. We've stayed friends ever since."

John added: "When you share that kind of meteoric success - and nothing has been able to exceed it - you share a bond. I've been through her having a child, getting divorced, losing her sister. She's been through my getting married, having children. It's wonderful and full of shared memories."

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However, fans hoping for a full-on 'Grease' reunion will be disappointed as Olivia previously admitted she thinks it is "a bit late now" for a reunion.

She said: "I think it's a bit late now. What would you do? Put us in a nursing home? I can't imagine that working now but you never know what someone could come up with. If there was a great idea then, of course, we would consider it, or at least I would. If John was up for it, then I think I would be too but we couldn't do it without each other. Let's see what the future brings."