I'm in the Philadelphia PA suburbs, and I know a "Shaz". More accurately, I should say that I know a Sharon (also a resident of this area) who is called "Shaz" by one person. That person was raised in Jackson Hole, Wyoming, although both of his parents are from this area. I'm not sure where the guy picked up his knowledge of the existence of the nickname, though he is a Vietnam War veteran and may have been acquainted with Australians there who used the nickname.

However, I'm not able (or willing) to ask him about it, because he is my ex-boyfriend, and he left me for "Shaz" !

(She, at least, fits the stereotype of the promiscuous, bubble-headed Essex girl, but I certainly would like to think that I do not!)