Out of nowhere, just remembered another sort-of "series" that I was writing in my 20s and maybe into my 30s -- a running gag called "2 Kinds of People." (I'm sure thousands of people have independently come up with the same gag.)

Every now and then I'd observe someone doing something and think "well there's 2 kinds of people; people who do that that way, and people who do that this way." You write down enough of those, it starts to look like a bit.

I'm sure it was a Word file; can't find it anywhere. Alas.