I did not know this:
In the spirit of our recent hosting of the Tar Heel Tavern blog carnival and our general posts on debunking alternative medicine, I learned today about the source of these two words with ties to the homeland.
Miss Cellania's always informative posts at mental_floss blog linked today to Neatorama's, 10 Insulting Words You Should Know. The outstanding list, which you should read in its entirety, includes the origin of the word, "bunkum," which is derived from Buncombe County, NC:
In 1819, a North Carolina congressman, the Honorable Felix Walker, was giving a rambling speech with little relevance to the current debate. He refused to yield the floor, and claimed that he wasn't speaking for Congress but instead "for Buncombe" (a county in North Carolina he represented). That's all it took.
Over time, the spelling changed to "bunkum," and the meaning strangely changed to be "excellent." Then it changed back in 1870, when a San Francisco gambler introduced a new game "banco" played with dice that were later found out to be loaded. Sure enough, BUNCO became known to mean swindle or cheat, and bunkum reverted back to its original meaning. (Source)
The word DEBUNK came directly from this: it's just bunk(um) with the prefix de- (meaning to remove).
With apologies to my friends in Buncombe County, home to the glorious city of Asheville.