The origin of "Trick or Treat"

The secular tradition of trick-or-treating has its roots in both the pagan and
Christian holidays. The practice can be traced to the original Halloween, known
as Samhain, an ancient Celtic New Year's festival during which human and
animal sacrifices were made to the Lord of the Dead and the sun. During
Samhain, after offering a feast to the dead, masked and costumed villagers
representing the souls of the dead paraded to the outskirts of town leading the
ghosts away. In medieval times, Christians dressed as their favorite saints for the
All Hallows procession.

There is also a possible connection with Guy Fawkes celebrations of
post-Renaissance England. In these, children dressed up as the executed
conspirator to beg "a penny for the Guy" from passing strangers. A traditional
Irish custom on Samhain eve was the soliciting of contributions in the name of
Muck Olla, a shadowy Druidic figure who would be sure to wreak vengeance on
the ungenerous. Muck Olla's vengeance gradually became transformed into the
tricks of disappointed human revelers.

Now a word question: How in Sam Hill is "Samhain" pronounced?