From a reader:
If I remember correctly, in the movie Airplane, “golly” was the english translation, via subtitles, from an early scene where the black actors spoke jive (where June Cleaver translated some of it and subtitles took care of the rest) of a word that starts with the letter “s” and rhymes, strangely enough, with the word Mitt. Ever since the movie Airplane, golly has found its way into my vocabulary as a substitute for that word.