Thanks, Bill, you're right that it comes from the pronunciation. It's one way we have of checking whether someone is a dinky-di Aussie. If they pronounce it as Oss-ie (with an "s" sound, and breaking it into 2 distinct syllables) then they are probably not from here, and are more than likely from America. We say it like "Ozzie" - with no break in the word.Originally the term caught on in about the 70's when a couple of left-wing, lateral thinking, intellectual crazies (and I mean that in the nicest way) started a controversial magazine called Oz. It was sort of an antidote to the yobbo (i.e. redneck) characteristic which was attached to Australians overseas.
When I use the name Oz I tend to be saying it with a sort of wry, self deprecating humour (another characteristic of Oz - we never miss a chance to laugh at ourselves.)
Helen