Cracker. From wordorigins.org:

Throughout the American South, poor, white trash are referred to as crackers. The most common explanation for the origin of this phrase is that it is from corncracker, or someone who distills corn whiskey (cracking corn is to crush it into a mash for distillation). The song lyric Jimmy Crack Corn is a reference to this. In the song, a slave sings about how his master was thrown from his horse when it was bitten by a blue-tail fly, hit his head, and died. And the slave "don't care." (This was a pretty subversive song for its day.) This is not, however, the origin of the ethnic term cracker. The term corncracker is first attested to only in 1835, well after cracker was established as a term for a white man.

Another common false etymology is that the term comes from the crack of a whip. This tale has the origin in white overseers of slaves, or "whipcrackers," who brutalized their charges. Again, this explanation has no evidence to support it.

Instead, cracker comes from an old sense of crack meaning to boast. This sense dates to the 15th century and is still in dialectical use, mainly Scots, in Britain. A 1766 quote in the OED2 gives the origin of cracker as boastful.

No reason for posting this other than that I found it interesting. That, and this season's cast of "Big Brother" is almost exclusively made up of crackers. These shows generally aren't representative of the population, and I'm not saying that they absolutely have to be. But this might be the whitest group on a reality show during the reality show plague over the past six years. 40 million Latinos in this country, and they can't find one to go on there? 10 million Asian-Americans? I'll have my research department do some investigating into the matter.
(And to be fair, TAR isn't much more representative, though there is an overabundance of stupidity judging from last night's show.)