You would say chasm as in that great Cockney sonic ejaculators Chas-n-Dave-m if you weren't aware of the hard ch. I'm forgiving, I learned from books, which means you grow up to snotty people saying don't you mean? and then delivering their very correct pronunciation. Generally, I'm gracious about their correction, before burying their bodies somewhere they won't be found.
Listening to a presentation at the moment by a French lady. On every other slide there is the word 'focus' which she delivers so it sounds like a bit like 'fuck you.'