Green’s Dictionary of Slang

doodinkus n.

also dinkus, dodinkus, dudinkus
[ety. unknown]

any nameless small object, typically some form of gadget.

[US]DN III 543: Doodinkus.
[US]J.C. Ruppenthal ‘A Word-List From Kansas’ in DN IV:ii 105: dinkus, n. Thing; jigger. Also dodinkus, dudinkus. ‘This little dudinkus belongs to an automobile.’.
in L. Perkins Flight into Yesterday 182: The whole doodinkus is suspended from the roof or ceiling so as to hang a few inches above the floor line.