I tripped over the word 'gaol' in a wikipedia's article once. I knew what it meant, but had no idea it had been used since the time of Chaucer. Changed it to 'jail' and sparked an international incident.
First ever encounter with it was Elden Ring. Couldn't for the life of me ever figure out WTF it was and just kept ignorantly pronouncing it "gowl" in my head.