A Meaning of Christmas

The Froochalans have always loved Earth, a fascinatingly bizarre planet with some truly indecipherable traditions. Why are Earthlings the way they are? Why do they all suddenly bustle around and act busy once a year? What is the actual meaning of this "Christmas?"
Well, when you're a highly technologically-advanced multidimensional and super-rich race, you know how to deal with any question: send some fairly bright Froochalan down there with an MDRD and a cloaking device and let him sort it out. Poor Daxqthu is about to find out what most humans spend their holiday seasons trying to avoid....