Persons ready to quarrel for anything. The allusion is to the jugglers who “eat” flaming tow, pour melted lead down their throats, and hold red-hot metal between their teeth. Richardson, in the seventeenth century—Signora Josephine Girardelli (the original Salamander), in the early part of the nineteenth century—and Chaubert, a Frenchman, of the present century, were the most noted of these exhibitors.
“The great fire-eater lay unconscious upon the floor of the house.” —Nashville Banner.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894