dud (n.)youdaoicibaDictYouDict[dud 词源字典]
c. 1825, "person in ragged clothing," from duds (q.v.). Sense extended by 1897 to "counterfeit thing," and 1908 to "useless, inefficient person or thing." This led naturally in World War I to "shell which fails to explode," and thence to "expensive failure." [dud etymology, dud origin, 英语词源]