I asked the local deepseek-14b in my basement what it thinks and bolded the part that was also my answer.

Q: Can you explain referring to sex as "screwing"? Doesn’t that imply some rotational energy the act doesn’t have? Unless I’m doing it wrong. And although screws DO go in and out, they do it awfully slowly. If we’re going to use mechanical metaphors, wouldn’t “pistoning” be more apt?

Hmm, I can see where they're coming from. Metaphors are tricky because they try to draw parallels between two different things, but sometimes those parallels aren't perfect. Let's break this down. First, why do people use "screwing" for sex? Well, the term probably originates from the physical action of screwing something in, like using a screwdriver. The movement involves turning and pushing, which might have been likened to the movements involved in sexual intercourse.

But wait, when you screw something, it's more about rotation and maybe some linear motion as you turn the screwdriver. However, during sex, while there is an in-and-out motion, it's not rotational. So why the term "screwing"? Maybe because both involve a kind of forceful entry or movement?
Or perhaps it's just that the word became slang over time and stuck, even if the mechanics aren't exactly the same.

Then, the person points out that screws go in and out slowly, but sex is usually faster. That's another point—metaphors often simplify things, so maybe "screwing" is used not because of the speed or movement type, but more for the idea of fitting together or forcing entry.

As for suggesting "pistoning," they're right that pistons move in a cyclical in-and-out motion, which might be a closer fit to how sex is sometimes described. But why isn't "pistoning" the term used instead? Maybe because "screw" has a stronger connotation of force and assembly, which are aspects people associate with sex.

I wonder if there's also a historical or cultural reason for using "screwing." Maybe in certain contexts, it was considered more vulgar or descriptive than other terms. Also, metaphors often stick based on how they're popularized in media, literature, or even slang usage, regardless of their technical accuracy.

Another angle is that "screwing" might evoke the idea of紧固 and fitting together, which could metaphorically relate to intimacy. So it's not just about the motion but also about the connection between people. On the other hand, "pistoning" seems more mechanical and less about the emotional or intimate aspect.

But then again, maybe the person is overthinking it. Sometimes metaphors are used because they're catchy or have a certain rhythm in language, even if they aren't technically accurate. For example, saying "making love" is poetic but doesn't describe the mechanics either.

I also think about other sex-related terms, like "dancing," which emphasizes movement and rhythm over specifics of motion. So maybe "screwing" just stuck because it was a term that described the act in a way that was understood at some point, even if the metaphor isn't perfect.

In conclusion, while "pistoning" might be a more accurate mechanical metaphor for the in-and-out motion, "screwing" has its own history and connotations that make it a common slang term. Metaphors often don't need to be technically precise; they just need to resonate or convey an idea effectively, even if imperfectly.