ADHD is when high school chemistry class covers emulsifiers and you remember it

I do remember that (one of a few things I remember from HS chemistry) - but I fail to see how it relates to the question of whether to water the toothbrush before putting on toothpaste, vs. watering after or not at all.

This has been the exact opposite of my experience. It feels as if I can't remember what happened yesterday, let alone during my school years.

Why does remembering a topic covered in school mean having ADHD?

It doesn't. I was being sarcastic :)

But can’t remember if you ate today or not.

It's 5PM and I haven't eaten yet, good reminder. /joking-but-factually-true

I have a really bad episodic memory and my sense of hunger stopped working normally in my teens. It's got nothing to do with anything else.