Grease

There's undeniable chemistry between John Travolta and Olivia Newton-John - in fact, it's electrifying - in the chart-topping, dancefloor-filling, feelgood musical romance between two star-crossed lovers at a 1950s California high school. She's a good girl who has to play bad to land a bad boy who's really quite good. The perfect soundtrack to happy days - and, uh, summer nights.