- Very likely based on analogy to happy-go-lucky. However, the part of speech of spending and lucky do not appear to match up. This could be based on an understanding of happy-go to mean happy to do something. This would point to why the last component is a participle and not an infinitive form. It is also a compound of the three roots in an adjective-verb-verb compound.
happy-go-spending
adjective; analogy
buying prodigiously and in a carefree way
Etymology : from happy ‘carefree’ (originally favored in luck), go ‘to leave for a place’ (from PIE *ghe 'to release'), and spend ‘to use money’ (from a clipping of either Latin dispendere 'to pay out' or expendere 'pay down')
Source : (September): “Americans after WWII were happy-go-spending” (Growing Cities documentary)
Last modified: 30 November 2017