I have a vague memory of once coming across a word like “neck” or “back” or some other word spelled with a “ck” that had been misspelled on a chalkboard with two “c’s” so it came out as “necc” or “bacc”. (And no, it wasn’t in that sorta cutesy way that animal memes do.) I went over and corrected it, being the stickler for spelling and grammar that I was (I was about 10 or 11 years old at the time), but then one of the other kids changed it back.
The explanation they gave me was that “ck” was supposed to stand for “crime and killing” or something stupidly fake-gangster like that, and that you weren’t ever supposed to spell a word with those letters. I decided to let it slide at the time, but looking back on it, it’s one of the most ludricuously absurd things I’ve ever heard of. Who invents idiotic rules like that and who bothers to enforce them?? And why??