@Volttekka @mionAnR Tsunderes can be found in Manga and Anime from at least as far back as the 70's if not earlier. I'd have to say that my first run in with them was from Rumiko Takahashi's works Ranma 1/2 (mostly in Akane) when I first started learning about manga in the 90's. Her earlier works also showed this in the 70's with Lum. Most people these days know her works from InuYasha and I suppose now YashaHime.
If you know that history, then it's not unreasonable for someone 50+ to know the character type of a tsundere character.
Outside of anime and manga, you'll also often see them with parents (usually dads) who say no pets, you're not getting a dog, or cat, and then them being the one who tends to them the most, and that has existed for ages.
Flags are also the same. While Death Flag was I think one of the oldest terms I've heard, events in media (and sometimes real life) and the belief in curses and luck are where I've seen it originate. You know, the kind where a person says that he'll marry his girlfriend when he gets back from the war, or someone saying he'll fulfill a promise after he catches some criminal. It wasn't until visual novels (or references to them) just called it a flag (since it wasn't necessarily death).