It is 45 years since Grease became the word, Olivia Newton-John shoehorned herself into one of the tightest pair of pants in movie history and John Travola wella-wella-wella-umphed his way around high-school to a pulsing Bee Gees soundtrack. In honor of the anniversary, Travolta took to his Instagram account to share a behind the scenes clip from the premiere of the movie and remember the “great day” they had at The Chinese Theatre in Hollywood.