Green’s Dictionary of Slang

jim-jam n.

[ety. unknown, but of similar pattern to flim-flam n.; whim-wham n.]

a fanciful or trivial article, a knick-knack.

[UK]Nashe Pierce Penilesse 31: A thousand iymiams and toyes haue they in theyr chambers.
[Aus]M. Garahan Stiffs 37: To earn five shillings per diem I must sell two hundred of these jim-jams.