He would answer to “Hi!” or to any loud cry,
  Such as “Fry me!” or “Fritter my wig!”
To “What-you-may-call-um!” or “What-was-his-name!”
  But especially “Thing-um-a-jig!”

Always assumed that thingamajig derived from Lewis Carroll’s thing-um-a-jig (1876).

I’d seen an oft cited but unsourced reference to 1824 in dictionaries but now found it: June 1824 issue of The Casket a literary monthly “all the cute and curious thingumajigs of the Old Colony.”

— Sandy Slynn (@Sandy_Slynn) February 17, 2020

See also: and

2020-02-25, update: 2022-04-19

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