I get really worked up by how incorrectly people use 'A' or 'An'. It literally will bug me for hours.

I'm not gonna google if both are acceptable to whatever extent, because only one way makes sense. 'An' goes before a word where the first syllable is pronounced with a proper vowel (so 'y' doesn't count). It's to stop consecutive vowel sounds. That's it. It's not "an euro", its "a euro", because it's pronounced with a 'Y' rather than a proper vowel. If I was talking about the letter 'F', I would say "an f". Sure, it makes me feel pedantic, but it just rattles my brain for far too long, thinking about how i should chill out, put myself in the brain of someone who thinks like this, its just a mistake... and it just seems as absurd as miscounting your fingers. Please excuse me for sounding rude, but it seems more prevalent on reddit (my access to predominantly American culture) than I've experienced in Europe. Is it just me?