Grease stars John Travolta and Olivia Newton-John enjoyed a mini-reunion on Friday night.

The two actors have remained firm friends since they made the iconic movie-musical in 1978 – they even recorded a holiday album, This Christmas, together in 2012. But as Newton-John wrote on Instagram, this marked the first time in more than 40 years that they've reunited in their original Grease costumes. The occasion was a sing-along screening of the movie followed by a Q&A with the stars at the Coral Sky Amphitheatre in West Palm Beach, Florida.

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Travolta also shared pictures from the event on Instagram, revealing that Newton-John found time for a mid-event outfit change so that fans saw the "good girl" version of her Grease character, Sandy Olsson, as well as the wilder, black-leather wearing Sandy from the end of the movie.

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The reunion marked a double-whammy of Grease nostalgia for Newton-John. Earlier in the week, she was presented with her black leather jacket from Grease by a fan who had paid a massive $243,200 for it at a charity auction. You can watch a video of the heartwarming moment on Facebook.

Originally released in 1978, Grease became a surprise pop culture phenomenon and, at the time, the highest-grossing movie-musical ever. Home to hits including "Grease is the Word" and "Summer Nights," the soundtrack album has sold an estimated 38 million copies worldwide, making it one of the best-selling albums of all time to this day.

Which is your favorite song from Grease?