- Marty: "What if I go back to the future and end up being... gay?"
- Doc Brown: "Why shouldn't you be happy?"
- — Deleted scene from Back to the Future.
During the 1960s, the word "gay" came to assume its modern meaning, "homosexual." This is now its only recognized meaning, and as such was used by President Obama in his inauguration speech.
In 1955, however, just as it was impossible to imagine a "colored mayor", let alone such a President, the word "gay" had a different meaning. It was a synonym for "happy" and "joyful," and was regularly used with this meaning in the songs of time (Perry Como sings, "Look at them sway with it/ getting so gay with it" of a husband and wife dancing with each other in Papa Loves Mambo, the song playing on Biff's car radio on the way to the Enchantment Under the Sea dance).
A scene deleted from Back to the Future extends the conversation Marty and Doc Brown have before Marty takes Doc's car to the dance. Marty expresses the fear that "feeling up his mother" could make him gay (homosexual) when he comes back to 1985. The 1955 Doc, already a victim of Marty's futuristic phraseology with "This is heavy", replies there's no reason why Marty shouldn't be happy.