piss off (v.)youdaoicibaDictYouDict[piss off 词源字典]
(intransitive) "go away," 1958, chiefly British; (transitive) "annoy," 1968, chiefly U.S.; from piss (v.) + off. Pissed off "angry, fed up" is attested by 1946 (Partridge says 1937); said to have been used in the military in World War II; in common use from 1970s.[piss off etymology, piss off origin, 英语词源]