Origin: 1870–75; thingum or
thingummy +
jig 1 , metrically patterned like
gobbledygook,
rigamarole; thingum perh. orig. from the gradational compound
thingum-thangum (based on
thing 1 ) with the same terminal syllable as in
crinkum-crankum,
harum-scarum, trinkum-trankum, the ult. orig. of which is unclear
