The word 'gay' in the film referenced homosexuals...
I'm not sure if this is all correct, but considering my professor had tought the field for a while, I'm going with him on this one.
After watching "Bringing up Baby," my college professor said that the word "gay" used in the film is actually describing homosexuals. Firstly, many people have pointed out that "gay" came to be a popular term in order to describe homosexuals in the 1960s, but according to my professor, the Los Angeles area (which had quite a few homosexuals at the time, especially in hollywood) used the word gay even before it became the popular way to term homosexuals. Secondly, if I'm not mistaken, he also said that it was an improvisation by Cary Grant and Grant, being a hollywood star, knew the term gay from people he met in hollywood. Thirdly, it passed by the censors because many who headed the censorship board thought the word gay meant happy, which was commonly the case at that time. It was kind of like an inside joke I suppose...
My professor also told us some interesting trivia like how the writers actually had a wild, homosexual love affair while they worked together on the film... Well anyways, I hope that helps the debate...