"I could care less" instead of "I couldn't care less."

Well, most Brits would rail against the former. The trouble is that both expressions are in use and have been for many a decade, the latter for longer, admittedly, and they mean the same thing. It's a another battle that you'll lose if you can be arsed to join it. Whether we like it or not, both expressions are standard English. Let's just enjoy life.