I was going to post this under the Geezers tag, since I’m not sure many people reaching adulthood today would quickly identify this as a reference to Porgy and Bess. But then I realized that Porgy and Bess was well before my time as well, yet I don’t think it odd that I understood it and I’d expect most people my age to recognize it as well.
The difference, I think, is that when I was growing up, entertainment was more communal: Instead of every family member scattering about for their separate entertainments — computers, DVD players, cell phones, whatever — there was a television set. Usually one in the house and if you lived in the right city, and the Reception Gods were being kind, you might be able to tune in all of seven different stations. So you watched what your parents watched, and probably your neighbors were watching the same thing. You were exposed to Bonanza because your father liked it, and to old movies because your grandparents liked them, and just about everybody growing up had the same cultural reference points (justĀ walk over to a crowd of people my age and say “A horse is a horse” and see if anybody doesn’t respond).
For what it’s worth, there were two metatexts for this one: “Semmelweis reflex” and “Alternative Title - Cognitive Heuristic Shortcuts Commonly Employed by Members of Primitive Hominid Societies on Undeveloped Class M Planets.”
Is there some internal logic by which “belly up” means “financial success” to a lingerie company? And, while admittedly I’m not an expert on the subject, isn’t she handing over a bra, not a slip?