That was the traditional cry at the door when we went trick-or-treating as a kid. We used "trick-or-treat" too, but mostly it was kids shouting "Halloween apples!". No idea where it came from, but that's what we did.
I've never been much of a Halloween person, and was never really into getting into costume or going trick-or-treating as a kid. Most of the time there was snow on the ground already, so there wasn't really much point in dressing up because you had to put a coat on top of the costume anyway. We always had lots of kids at our door though back home and usually stayed pretty busy handing out candy and dropping change for UNICEF into the little orange boxes.
Last week, we bought a couple of bags of candy to hand out to the expected trick-or-treaters. A few days ago, the wife bought some more, having forgotten that she already bought some several days earlier. I know there are a few families in the area so we were expecting a few kids trick-or-treating yesterday. Only 1 kid showed up at our door last night. Perhaps we missed them because of coming home a little bit later than usual. Perhaps kids don't go trick-or-treating anymore like we used to. It's definitely become a much more paranoid time than it used to be when I was a kid. I remember when I was back home working at the hospital during my undergrad, the x-ray department in the ER would be busy x-raying buckets and bags of candy that kids and their families brought in. Nothing was ever found though. But the paranoia remains. Kinda sad, I suppose.
In any case, we have a bunch of candy left over now. Darn :)