In the context of the scene, it would seem that when the Cary Grant character said, "Because I just went gay all of a sudden!" it would seem not to mean “gay” as in “happy or carefree” but in the other sense as it was in answer to why he was wearing a frilly woman’s robe, but it could be taken that way as well. But then it would have made more sense to say “I was just feeling gay all of a sudden”.
Bringing Up Baby - "Gay All of a Sudden"
The word gay was long meant to mean "joyful", "carefree" or "bright and showy" but it did have a more negative usage going back to the late 1600’s to mean uninhibited or without moral constraints, loose or promiscuous and could apply to either men or women, presumably straight. The use of the word gay to mean homosexual, goes back to the late 19th century or at least the 1920’s but wasn’t in much regular usage in that way and was more often still associated with the earlier meanings of being happy and carefree until the 1960’s.
I grew up in the 1960-70’s and even as a kid, I knew that in a certain contexts, “gay” meant homosexual or as my father used to refer to them; “light in the loafers”, “poofers” or “Nancy Boys”, even if back then I didn’t completely understand all of what that meant, I did understand it to mean a man who was effeminate and preferred the company of other men. I also knew that when the Flintstone’s theme song said “We’ll have a gay old time” they didn’t mean that Fred was hooking up with Barney and Wilma with Betty.
Interesting that there’s such a long history of the word. I really don’t think I ever heard it used ‘that way’ until late 70s as the homosexual lobby was gathering steam. (around the same time abortions became ‘choices’)
Yes, it is really too bad about “gay”. Song writers loved it because it rhymed so well with so many words...day, may, say, way etc... Our high school choir director wanted to include a patriotic segment in a recent school program which included the song “When Johnny Comes Marching Home”. At first she wanted to change the “We’ll all feel gay” line to “We’ll all be glad” but at the last minute she changed it back.
As another poster has said, I also refuse to call homosexuals “gay”.