Sarah Michelle Gellar's Grease theory: Sandy was actually dead the whole time

Goodbye to Sandra Dee?

Sarah Michelle Gellar's shared a mind blowing fan theory about the massively popular musical film Grease.

The Buffy star took to Facebook to share the theory which essentially says Sandy - the film's leading lady - is actually dead, and the whole film is just a fantasy scenario.

She wrote: "At the end of the movie, Danny Zuko and Sandy Olsson fly off in a red convertible as they wave goodbye to their friends on the solid ground below, leading to the conclusion that the flying car was the final result of Sandy's fantasy. (As in she is dead)."

The theory provides further "evidence" by deconstructing the lyrics of the song Summer Nights, in which Danny and Sandy tell the story of how they first met and began a summer fling.

"The line, 'I saved her life, she nearly drowned,' suggests that Sandy actually did drown and the whole movie is an elaborate musical fantasy due to the lack of oxygen getting to her brain.

"The flying red convertible also suggests that Sandy is happily being whisked away to heaven at the end of the movie."

In the comments on Gellar's post, fellow fans added their own theories.

One wrote: "It means that when she starts to smoke and giving in to peer pressure at the finale, she is basically 'letting go' and accepting her fate and able to ascend to her 'own heaven' with Danny."

Is this Sandy finally accepting her fate?

While another added: "It does explain a lot though...the car restoration scene, and Frenchie's song to name a few."

The theory actually originated on Reddit, where other fans are continuing to post similarly dark theories including one which says Sandy killed herself toward the end and that's what the song "Goodbye to Sandra Dee" is about.

Another suggests both Sandy and Danny drowned at the beach that fateful day, and Danny could even have made up Sandy's name in his fantasy because of all the sand on the beach.

Probably a stretch, but an excuse for a re-watch nonetheless.