One of the most notable Christmas traditions in Mexico is the reenactment of Mary and Joseph's journey to Bethlehem, when they were denied rooms at various inns and finally found shelter in a stable.
During the Posada, a group with candles (representing Mary and Joseph) go from door to door singing a little tune and being "refused" until they come to the end of the pageant - the final home - where they are finally offered a place to stay.
Nowadays, the word Posada is synonymous with "Christmas Party." Perhaps the most important part of the party (for the children) is the breaking of the piñata and the ensuing sugar-fest.
Feliz Navidad a todos!