Why do authors seem to treat it as a requirement to use the word "pussy" instead of vagina, vulva, or just genitals?

[PantsDownFun]

Similarly, in a different story, a younger boy asked the older boy in the room about the genitals of the naked girl that was in the room. The older boy then responded with something like this:

"Well, the actual name for it is the vagina or the vulva, but you can call it a pussy or a coochie..."

The younger boy then decided on coochie because he liked the word.

I have seen this kind of thing in many stories, and I am just wondering...Why?

I'd like to also add, for a native English speaker "vagina" in particular is a little awkward to say. It's three syllables with a kind of awkward vocal pause in transition between them so it does not roll off the tongue (add your own joke here) and there aren't many other frequently used words constructed that way or that begin with "vuh" like that.

Conversely, virtually everyone learns the word "pee" from a very young age and "penis" is closely related in sound and easy to connect mentally.

In my mind that makes it attractive to swap vagina for a two-syllable slang word that people find easier to say.

It is worth adding, while three syllable words aren't uncommon, most three syllable words tend to accent the first and third syllables, vagina accents the first and second. That might be what is going on with that "awkward pause"