Dear Little Old Mrs. Vandertramp

All of us who learned French as a second language learned about Mrs. Vandertramp. None of my francophone friends have ever heard of her, and they think it’s the funniest thing they ever heard.
In French, there exists a handful of verbs which are not conjugated in the usual way with avoir, but with être. It just so happens that their first letters, arranged artfully, spell Mrs. Vandertramp. Careful students of French will protest that a few verbs get left out, but you can’t let reality get in the way of a good mnemonic. Careful students of French will also point out that the rule only applies to the person, not to things, and that they are almost adjectival in their operation.
English verbs used to be conjugated in exactly the same way, and one still hears the structure from the mouths of very careful speakers. Shakespeare and the King James Bible use the old form “When Jesus was come down from the mountain” rather than “When Jesus had come down from the mountain”. Same deal– descriptive of a personal change. But in English, that’s all but archaic.
It turns out that learners of English as a second language are faced with arcane and incomprehensible rules, too. Consider the order of adjectives, for example.
Suppose I give you these five words, and ask you to arrange them into a normal English expression: grandmother, Norwegian, old, nice, little.
Almost certainly you said “Nice little old Norwegian grandmother”. So did I. Why? We have no idea, do we? But apparently there is a rule about the order of adjectives, and apparently learners of English as a second language have to sweat it.
It seems that the rule of adjective order is opinion, size, age, shape, colour, origin, material, purpose. Most of us have never heard of it, but all of our anglophone brains agree that’s the order of things.
That’s the funny thing about language– rules are cooked up after the fact to try to explain things, but in reality, our incredibly complex minds simply have a deal amongst themselves about how to exchange ideas in a mutually agreed fashion.
Many years ago, as an anglo struggling to learn French, I spent inordinate amounts of time and effort looking for patterns that would help me determine the gender of French nouns– why is it la tasse, but le bâton? Finally, in exasperation, I implored my professor to show me some pattern or rule. He just roared with laughter. “C’est une question de foi!”– it’s a matter of faith.
And that explains a lot of things about life, doesn’t it?

(If your first language is something other than English, what’s the most puzzling thing for strangers to learn? I’d love to hear.)