One thing that puzzles me (apart from saying the time is 10 of 6??) is why Americans use the phrase 'I could care less' when the British equivalent seems so much more sensible. 'I couldn't care less'. If you could care less then by definition you care to a greater or lesser extent whereas if I couldn't care less then it doesn't mean anything to me at all. Is the American expression shortened from something you'd hear on Friends? 'Like, I could care less?'