doggone (adj.)youdaoicibaDictYouDict[doggone 词源字典]
1851, American English, a "fantastic perversion of god-damned" [Weekley]. But Mencken favors the theory that it is "a blend form of dog on it; in fact it is still often used with it following. It is thus a brother to the old English phrase, 'a pox upon it,' but is considerably more decorous."[doggone etymology, doggone origin, 英语词源]