I'm starting an ongoing tweet thread of offbeat edits and arcane AP Style guidelines I stumble across on the job (mostly because I typically post these in Slack where nobody reads them
). Here goes:

A tenant is someone who lives in someone else's property.
A tenet is a principle or belief.
A tenet is a principle or belief.
That ubiquitous piece of lumber is a "two-by-four."
For some reason, the AP suggests "drive-thru" and not "drive-through," even though it says "doughnut" and not "donut."
A few AP Style preferences for proper nouns and then I'll wrap it up for now: PricewaterhouseCoopers is "PwC" in first and all references. The Bahamas is singular. And they switched from "Kiev" to "Kyiv" last year after the Ukrainian government declared it the preferred spelling.
You want arbitrary? Check out newspaper names. Some newspapers have a "The" in their names that needs to be capped. Some don't. Some don't actually have cities in their name, even though that's how they're commonly known. Here's a super fun list: https://www.poynter.org/reporting-editing/2013/newspaper-title-style-guide/
A mishmash of AP Style items from today's editing: civil rights era/movement (though there is some argument in favor of it being uppercase), "schoolwork" and "hairstylist" are one word but "child care" is two. And, puzzlingly, the thing that precedes kindergarten is "pre-K."
Also remember that they changed their ruling on spelling out percent when used with a numeral last year â it's all about the % now â to the consternation of many veteran journalists. https://www.poynter.org/reporting-editing/2019/ap-says-the-percentage-sign-now-ok-when-used-with-a-numeral-thats-shift5/
Cruise line, two words. Airline, one word. ÂŻ\\_(ă)_/ÂŻ