Just found this on 1800flowers.com

What's The Story?
In Scotland, according to tradition, children usually recite "The sky is blue, the grass is green, may we have our Halloween" instead of saying "trick or treat!" The groups of children must also impress neighbors with a song, poem, or dance in order to earn their delicious treats.

Up here it is "Trick or treat, we want something good to eat" and often there had to be a song, poem or dance of some sort. Now there's just too darn many kids coming at once. Let me not even get into the parental politics.