Sorry "Grease" fans ... Sandy didn't die while Danny tried saving her and the whole film ISN'T her vivid coma fantasy ... according to one of the creators.
Jim Jacobs, who wrote the original book and musical with Warren Casey, is shooting down the conspiracy Sandy was dead during the whole film. He tells TMZ whoever made up the theory must have been on acid.
A theory's been flying around that Danny hadn't been able to save Sandy after someone linked the "Summer Nights" lyrics, "I saved her life she nearly drowned," with the final scene in the movie where the two take off in a flying car.
Jacobs says, although there are differences between the book and the movie, one thing is certain ... Sandy was very much alive and the real phenomenon is that "Grease" is still popular over 40 years later.