More than 40 years after Grease dropped, stars John Travolta, 65, and Olivia Newton-John, 71, reunited as Danny and Sandy at West Palm Beach’s Coral Sky Ampitheater for a sing along Friday. First she donned a yellow cardigan and matching skirt a la “good girl” Sandy, then ditched them for a leather jacket and black leggings, like the ones she wore in the Grease finale. The pair also held a Q&A.