The most notorious fan theory suggests that Sandy is in fact dying throughout the movie and the story only plays out in her imagination. Arguably one of the most famous movie theories of all time, it offers a completely different perspective on the movie's otherwise mostly upbeat tone, adding darkness to the musical's joyous light. And while the theory has its detractors, it remains incredibly popular, because it is tied to the film's strangest mystery: what its end really means. It is precisely because of that ending's weirdness and one particularly pertinent line from Grease's first big musical number - "Summer Nights" that a fan theory suggested a grim undercurrent to the classical musical including a dying teenage girl living her last moments "down in the sand". The fantasy sequences of "Greased Lightnin'" and "Beauty School Dropout", which very much play out in the imaginations of the characters singing those songs. The former is the T-Birds imagining their triumphs and how well the car will boost their boyish boasts of machismo, while the latter is Didi Conn's Frenchy imagining the bleakness of her future if her dream fails. Both are very much tied to dreams, but that makes the final sequence of Grease all the more confusing, because when Danny and Sandy fly off from the carnival in Greased Lightnin' it happens in real-time in the real world. Sandy's shock is nothing compared to that of the audience, who have just watched a fairly conventional high-school musical that operates within normal rules of reality end with a car literally flying off into the distance. In that respect, it was no wonder that there was an opportunity for a fan theory to fill in the gap in logic. The starting point of the theory, which was initially posted on Reddit, is one of the lines in "Summer Night" dedicated Sandy and Danny telling each of their listening audiences what happened during their holiday romance at the beach. While the Grease prequel, 'Summer Lovin', will tell the actual story of what happened during that tryst, the only account the audience can trust is the mention of the young couple bowling in the arcade, holding hands, and drinking lemonade. Crucially, the lyrics suggest that Danny and Sandy met when she got a cramp while swimming and Danny saved her from drowning, before showing off "splashing around". While it might sound like empty bragging, the theory suggests that Sandy actually did drown and everything that follows is Sandy fantasizing about what her life could have been as she dies. From the prolog onwards, every event that happens plays out in Sandy's mind, and the reason everything wraps up so perfectly for every character, despite all of the conflict on the way to the finale is that it's all Sandy's tragic wish fulfillment. As a newcomer to Rydell High, Sandy would have been an outsider, but her reality plays out just as a dream would; she is immediately accepted by the coolest group (the Pink Ladies), meets the boy of her dreams (again), and overcomes every issue. And it's not just her: Rizzo's pregnancy scare, the dance competition that Danny wins (albeit with Cha-Cha), the drag race on Thunder Road Everything ends with a happy ending, no matter what the seeming obstacles. It's all a little too convenient and then when Greased Lightnin' takes off for its maiden flight, the reason becomes clear. It's all a fantasy. The theory also suggests that Sandy's mournful reprise of "Look At Me, I'm Sandra Dee" and the final two lines "Take a deep breath and sigh, Goodbye to Sandra Dee..." specifically secretly confirm that Sandy lost her battle to live. In that respect, the image of Greased Lightnin' flying off with Danny alongside Sandy at the end of Grease is actually symbolic of her ascending to the afterlife and her transformation is not one of self-realization, but of death. That metaphorical rise, then, is her rising to heaven in the final moments of her life eking out with her final breaths on the sand. It's tragic and dark, but there is a hint of beauty to it. The theory gained enough attention that stars John Travolta and Olivia Newton-John both commented on it. The former called it fun, though told USA Today that he knew "the writers of Grease, and I was around in the original days. I can't take it too far." Sandy's actor, Olivia Newton-John herself called it "hilarious" and reveled in the idea of Grease being the first ever zombie musical. Unfortunately for fans of the theory, the most notable respondent to the theory was Grease creator Jim Jacobs, who wasn't as big a fan and poured water on the idea of Sandy being dead. He told TMZ that "Whoever made up the theory must have been on acid. Sandy was very much alive." But then, it's rare that the wishes of the creator are taken into account when fans come up with theories, and this one in particular actually does improve the Grease viewing experience, true or not.