By the way, I was surprised by this one: 'In the Forties everything was "copacetic".'

I don't think that appeared in my generation of Candians till the late '70's; I assumed it was new then. It was well-used for about ten years or so then. I see from an on-line dictionary, several sources trace it to the 1910s-20s.

Can anyone tell me why everyone starting using the expression "back in the day" about five or ten years ago?