also doohicky, a name for something one doesn't know the name of, 1914, American English, arbitrary formation.
Entries linking to doohickey
doodad n.
"unnamed thing," 1898, chiefly U.S., a made-up word (compare doohickey).
hickie n.
"love bite; mark on skin made by biting or sucking during foreplay or sex," 1934; earlier "pimple, skin lesion" (c. 1915); perhaps a sense extension and spelling variation from the earlier word meaning "small gadget, device; any unspecified object" (1909, see hickey and compare doohickey, still used in this sense).