jockstrap (n.)youdaoicibaDictYouDict[jockstrap 词源字典]
also jock-strap, "supporter of the male genital organs, used in sports," 1897, with strap (n.) + jock slang for "penis" c. 1650-c. 1850, probably from Jock, the nickname for John, which was used generically for "common man" from c. 1500.[jockstrap etymology, jockstrap origin, 英语词源]