Tinker's damn

Merriam-Webster finds tinker's damn in print since 1839 and suggests that it derives from tinkers' reputation for swearing. The spelling tinker's dam is attested since 1858, and phrases.org.uk notes the disagreement over whether the term originated from tinkers' swearing or instead from their use of small, single-use dams to hold solder. The latter explanation has been offered since 1877; on the other hand, the phrase tinker's curse is attested since 1824 and the phrase worth a tinker's cuss is attested since 1854, for which reason Etymonline considers the "dam" derivation an "ingeniously elaborate but baseless" invention of later writers.