As a noun meaning empty talk or nonsense, bunk has a well-documented origin. In 1820, when U.S. Congressman Felix Walker gave a long, irrelevant speech solely to delay voting on the Missouri Compromise, he said it was “for Buncombe,” referring to his constituents in Buncombe County, North Carolina. Buncombe instantly came to mean nonsensical talk.
Bunkum later become the more common spelling, though many writers still honor the word’s origins by spelling it buncombe. In any case, it’s usually shortened to bunk.
While buncombe is rare, it is possible to find 21st-century examples of bunkum:
The professor’s feral responses to personal criticism demonstrate that his professed dedication to liberty of expression is so much hypocritical bunkum. [ABC Online]
The police explanation, left largely unchallenged, is bunkum. [Globe and Mail]
But the shortened bunk is much more common. These writers use it in the conventional sense:
Much of what brokers, financial advisers and even some investors pass off as fact about the stock market is bunk. [Dallas Morning News]
First, the partisan notion that the “debt limit” belongs to President Obama is total bunk. [Daily Kos]
The last time a nation was asked to swallow such a load of bunk without reading the first page was in the 1930s in the Weimar Republic. [letter to Washington Times]