Why is noble not spelt 'knoble?'

I know I have already posted today, but this conversation, or statement more like, I heard on the bus keeps lurking in the back of my head. I think I stored it there for future reference but keep forgetting of which way I was going to reference it.

'No, don't say that again Rebecca. Don't talk like that. No, do you know what that's called? That's bitchin, girls.'

As said by the mother of Rebecca. I think they were 'bitchin' about the way a girl constantly boasted about herself, in a very careful manner mind you ('Do you...sometimes find that she always mentions her..um, awards?'. How very odd for a bunch of ten year old girls.).

This completely and utterly brightened my day.