One more thing about the Hollywood Production Code: ever notice that there were a few words or phrases that, because of their indeterminate meaning, could get into a picture and come off as "dirty" in a way that the censors might not have expected?
"Sex" was one such word. In conversation, it could mean sexual relations, but it could also mean, more generally, sex-appeal or sexiness or physical attraction (when it didn't just mean "gender"). So under the Hays Code some writers would slip in the word "sex" in such a way that it sounded like the (relatively) clean meaning of the word, but could be interpreted to mean sexual relations (which you weren't supposed to talk about openly in a movie). Preston Sturges did this several times.
Another term was "make love." When Jane Austen wrote that a man "made love" to a woman she was not, perish the thought, writing about sexual relations; to "make love" was to profess love, get romantic, and so on. This old meaning of "make love" was still in use in the '30s and '40s, but the new meaning of "make love" -- as a synonym for sexual relations -- was starting to spring up. So movie writers constantly used the term "make love" or "lovemaking," and to those in the know, it sounded dirtier than it actually was. (Pepe Le Pew used to talk about "making love" all the time, and whatever the censors thought he was saying, the real meaning is clear.)
And let's not even get started on the famous use of the word "gay" in Bringing Up Baby.