Green’s Dictionary of Slang

a person; often a foolish person.

[1825		J.T. Brockett North Country Words 106: Jigger, an airy, swaggering person. ‘A comical jigger’].
1894		J. London Tramp Diary in Jack London On the Road (1979) 61: I’m onto myself for a jigger w’en it comes to dem people.
1894		A. Morrison Tales of Mean Streets (1983) 60: Blowses in feathered bonnets bawled hilarious obscenity at the jiggers.
1914		Sport (Adelaide) 4 Sept. 5/4: Never mind, old jigger, plenty more fish in the river.
1919		Marvel 3 Mar. 2: Unless the jigger sells us a pup [...] we ought to beat the bank by a neck.
1925		D. Hammett ‘Corkscrew’ Story Omnibus (1966) 229: Did I do right, shooting that jigger?
1938		X. Herbert Capricornia (1939) 183: By cripes you dunno’t a wicked old jigger I am when I get rousted.
1947		W.D. Overholser Buckaroo’s Code (1948) 8: I’ve seen that jigger draw, and he ain’t slow.