Yours, Etc.: Origins and Uses of 8 Sign-Offs
1775, American English dialectal, "troublesome person or animal," an alteration of curse (n.), or else a shortening of the slang sense of customer.
"to say bad words," 1815, alteration of curse (v.). Related: Cussed; cussing. To cuss out attested by 1881.
A man; fellow; guy •Most use since the 1860s
[1775+; a shortening of customer; or perhaps ''one who curses'']