I'm obviously turning into a typical grumpy old cow. Nowadays I find the word 'cool' very irritating. I realise it means 'good', but why cool? And why do people here in my traditional Norfolk village always greet me with "Hiya!"? And instead of 'goodbye' or 'cheerio', they say "See ya later!"
But, having studied languages, phonetics, linguistics etc., I do see that all languages change and develop over the years. If not, we'd all still be talking like Shakespeare!