What is the X in X-mas?
1870, short for Limburger cheese (1817), from Limburg, province in northeast Belgium, where the cheese is made.
Some frauds a few years ago started a Limburger cheese factory down in Keyport, New Jersey, but the imposition was soon exposed. A man could come within 300 yards of the spurious article without being knocked down, and as the smell never had any effect on the town clock the business was soon discontinued. [John E. Boyd, "The Berkeley Heroine and Others Stories"]The place name is from Germanic *lindo "lime tree" + *burg "fortification."