Grease is a wildly popular American musical comedy film directed by Randal Kleiser and based on Warren Casey and Jim Jacobs’ 1971 musical of the same name about two lovers in a 1950s high school. Released in 1978, the film stars John Travolta, Olivia Newton-John, Stockard Channing, and Jeff Conaway.
It was successful both critically and at the box office. Its soundtrack album ended 1978 as the second-best selling album of the year in the United States, behind the soundtrack of Saturday Night Fever, another film starring Travolta.
Henry Winkler was once considered for the lead role in Grease. Winkler, who was playing Fonzie on Happy Days, was originally chosen to play Danny, but having twice already played similarly leather-clad 1950s hoods in 1974’s The Lords of Flatbush as well as Happy Days, turned down the role for fear of being typecast, so Travolta got the part. Olivia Newton-John was cast as Sandy at Travolta’s urging. – Edited from Wikipedia
Just before singing ‘Sandy’, Danny (Travolta) takes Sandy (Newton-John) to a drive-in movie and gives her his class ring, but then makes advances on her that offend her good girl sensibilities and send her running.