Anyone know where the custom of shouting "halloween apples" instead of trick or treat came from?

It is what they say in Winnipeg and I never got a straight answer for a reason other than that is what they are asking for. As a die hard Halloween lover I could never stand to hear that. Still curious though where it came from...
Update: Strange that I only ever heard it in Manitoba (hardly a roman celtic cultural hub) and I don't recall EVER hearing trick or treat at all. Thank the powers that I live in more a more civilized city now! (wink)
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