Green’s Dictionary of Slang

an indefinite expression used to describe a nameless object; also as dojiggie, dojiggum, dojiggus, dojiggy, dojimmie, dojinnie, dojisser, dojohn, dojohnnie.

1903		Salt lake Herald (UT) 28 May n.p.: If you have flags and bunting and other ornamental do-jiggers, get them out.
1905		L. Pound ‘Dialect Speech in Nebraska’ in DN III:i 66: Indefinite expression applied to something, the name of which is not readily recalled [...] doojohn, doojohnny.
1927		W.R. Morse ‘Stanford Expressions’ in AS II:6 276: doojigger — mechanical contrivance.
1922		Wkly Times-Record (Valley City, ND) 9 Nov. 3/2: Something went wrong with the do-jigger on the engine and held the train up.
1931		L. Pound ‘American Indefinite Names’ in AS VI:3 258: Indefinite names [...] dojigger.
1953		S. Bellow Augie March (1996) 345: Machine scarabaeuses, British and Belgian doojiggers, Manchester trolleys [etc.].
1960, 1975		Wentworth & Flexner DAS 156/1: doojigger A gadget.
1972		(con. 1916) G. Swarthout Tin Lizzie Troop (1978) 184: His hatred of the dojigger and the thingumabob was rekindled.
1986		S. King It (1987) 106: It was made of bright polished wood with lots of curvy inlaid lines and carved doojiggers in it.