dip (n.)youdaoicibaDictYouDict[dip 词源字典]
"stupid person, eccentric person," 1920s slang, perhaps a back-formation from dippy. "Dipshit is an emphatic form of dip (2); dipstick may be a euphemism or may reflect putative dipstick 'penis' " [DAS].[dip etymology, dip origin, 英语词源]