…the house elves are in Hogwarts too. They are not staff, they are school property. Harry owns a house elf after book 5. The books openly ridicule Hermione for being the only sane person and trying to end house elf slavery because apparently the house elves like being enslaved and she’s just overreacting. Need I go on?

Depends where you live, it’s somehow still alive and well in Poland! You’d usually use the lowercase xd for a more refined and low-key vibe tho, the full caps ones are reserved for special occasions.

In Poland we use standard qwerty keyboards with Polish keyboard layout set (called Polish Programmers), you press alt+character to get the special version (like alt+s gives you ś, alt+a gives you ą and so on, the only nonintuitive one is alt+x which is ź, because alt+z is taken by ż). Combine with shift or caps lock for capital versions. No issues.

Fun, but I don’t love the Polish word selection because a lot of these are supposed to contain special characters and they’re not actual real Polish words without them.

Like blad - that’s not a word. Błąd is a word, it means a mistake. So does this count or no? Or kal vs kał, one is a word (means feces) and one is just some letters.

It’s a reference to a meme that was particularly popular on Tumblr at some point, it’s called Apollo’s Gift of Prophecy Dodgeball, you can google that to see some examples. Basically when someone makes an obvious and ridiculous joke that (much) later turns out to be true, they were struck by the dodgeball of prophecy.