Why do we say "Trick or Treat"? Thank Guy Fawkes.

Where on earth did “trick or treat” come in? “Treat or treat” is perhaps the oddest and most American addition to Halloween and is the unwilling contribution of English Catholics.

During the penal period of the 1500s to the 1700s in England, Catholics had no legal rights. They could not hold office and were subject to fines, jail and heavy taxes. It was a capital offense to say Mass, and hundreds of priests were martyred.

Occasionally, English Catholics resisted, sometimes foolishly. One of the most foolish acts of resistance was a plot to blow up the Protestant King James I and his Parliament with gunpowder. This was supposed to trigger a Catholic uprising against the oppressors. The ill-conceived Gunpowder Plot was foiled on November 5, 1605, when the man guarding the gunpowder, a reckless convert named Guy Fawkes, was captured and arrested. He was hanged; the plot fizzled.

November 5, Guy Fawkes Day, became a great celebration in England, and so it remains. During the penal periods, bands of revelers would put on masks and visit local Catholics in the dead of night, demanding beer and cakes for their celebration: trick or treat!

Guy Fawkes Day arrived in the American colonies with the first English settlers. But by the time of the American Revolution, old King James and Guy Fawkes had pretty much been forgotten. Trick or treat, though, was too much fun to give up, so eventually it moved to October 31, the day of the Irish-French masquerade. And in America, trick or treat wasn’t limited to Catholics.

The mixture of various immigrant traditions we know as Halloween had become a fixture in the United States by the early 1800s. To this day, it remains unknown in Europe, even in the countries from which some of the customs originated.

http://www.ucatholic.com/blog/the-catholic-origins-of-halloween/