Halloween
http://en.wikipedia.org/wiki/Halloween On Halloween night in present-day Ireland, adults and children dress up as creatures from the underworld (e.g., ghosts, ghouls, zombies, witches and goblins), light bonfires, and enjoy spectacular fireworks displays, despite the fact that such displays are usually illegal. It is also common for fireworks to be set off for the entire month preceding Halloween, as well as a few days after. Halloween was perceived as the night during which the division between the world of the living and the otherworld was blurred so spirits of the dead and inhabitants from the underworld were able to walk free on the earth. It was believed necessary to dress as a spirit or otherworldly creature when venturing outdoors to blend in, and this is where dressing in such a manner for Halloween comes from. This gradually evolved into trick-or-treating because children would knock on their neighbours' doors, in order to gather fruit, nuts, and sweets for the Halloween f...