a coined variation of tinker's
damn, meaning something completely without
value or absolutely worthless. It is also used to
denote a
negligible amount (of something). A tinker is an itinerant mender of
pots and pans, generally held in low repute.
Doggone is a euphemism for
God damn. The
origin of tinker's
damn is uncertain. One
theory suggests that it came from the reputation tinkers had for profanity, dating back hundreds of years, and in swearing so much or so casually their words became meaningless or useless. Tinker's
damn is used in such phrases as not worth a tinker's
damn (meaning
having no
value) and to not
care a tinker's
damn (meaning to be completely indifferent, to feel little or no concern about something).