The duo, who played high school sweethearts Sandy and Danny, respectively, in the hit 1978 musical movie, reunited for a Meet n' Grease sing-along event on Friday, December 13 at the Coral Sky Amphitheater in West Palm Beach, Florida.
And during the event, Olivia and John wore two of the most iconic looks - Olivia wore a yellow skirt and cardigan and John a black leather jacket and skintight jeans to recreate their looks from the "Summer Nights" sequence of the movie, before changing into the all-black leather numbers they wore to perform "You're the One That I Want" in the finale of the movie.
"First time in costume since we made the movie ! So excited!!" Olivia wrote on her Instagram page.
It comes after Olivia was "blown away" after an auction winner who paid $243,000 for the jacket she wore in the final sequence returned it to her.
The auction winner, who described himself as the singer and actress' "number one fan," told the 71-year-old that after much thought, he'd decided the jacket "should not sit in a billionaire's closet for country club bragging rights."
Olivia, who is in the midst of treatment for her third battle with breast cancer, will now display it at the Olivia Newton-John Cancer Wellness and Research Centre in Melbourne, Australia.