Why are white people called crackers?

The origins of the term "cracker" are unknown, with multiple theories to explain its history.

One theory holds that the term comes from the common diet of poor whites. According to the 1911 edition of the Encyclopedia Britannica, it is a term of contempt for the "poor" or "mean whites," particularly of Georgia and Florida. Britannica notes that the term dates back to the American Revolution, and is derived from the cracked corn which formed their staple food. (In British English "mean" is also a term for tightfistedness, with no malice implied.)

Another theory is that slaver foremen in the antebellum South used bullwhips to discipline African slaves, with such use of the whip being described as 'cracking the whip'. In this folk etymology the white foremen who cracked these whips were thus known as 'crackers'.

An alternate whip-related theory is that the term is linked to early Florida cattle herders (Florida crackers) that traditionally used whips to herd wild Spanish cattle. These cowboys were distinct from the Spanish vaqueros of Florida. The crack of the herders' whips could be heard for great distances when they were used to round cattle in pens and to keep the cows on a given track. Also, "cracker" has historically been used to refer to those engaged in the low paying job of cracking pecans and other nuts in Georgia and throughout the southeast U.S.

Yet another theory is that the term derives from an Elizabethan word used to describe braggarts. The original root of this is the Middle English word crack meaning "entertaining conversation" (one may be said to "crack" a joke); this term and the alternate spelling craic are still in use in Ireland, Scotland and Northern England. It is documented in Shakespeare's King John (1595): "What cracker is this same that deafs our ears with this abundance of superfluous breath?"