cracker

[Gerald Cohen]

   For the etymology of slang "cracker" see RHHDAS, which presents a
1766 quote: "I should explain to your Lordship what is meant by
Crackers; a name they have got from being great boasters; they are a
lawless set of rascalls [sp.: sic] on the frontiers of Virginia,
Maryland, the Carolinas, and Georgia, who often change their places
of abode." So the term seems to derive from "crack" (British: talk,
speak; appears in "wisecrack"), rather than from the crack of a whip
or from corncracker.

--Gerald Cohen