What is the X in X-mas?
as a type of a childishly impractical man living in optimistic fantasy, from the character of Wilkins Micawber in Dickens' "David Copperfield" (1850).
"I am at present, my dear Copperfield, engaged in the sale of corn upon commission. It is not an avocation of a remunerative description -- in other words it does not pay -- and some temporary embarrassments of a pecuniary nature have been the consequence. I am however delighted to add that I have now an immediate prospect of something turning up ...."