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The Collaborative International Dictionary
piss off

piss off \piss off\, v. t. To anger or strongly annoy; as, his flippant attitude pissed off the teacher. [vulgar]

piss off

piss off \piss off\, v. i. To leave immediately; to scram; -- chiefly British, and sometimes considered vulgar. [Brit., vulgar]

Douglas Harper's Etymology Dictionary
piss off

(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.

Wiktionary
piss off

interj. (context UK Canada idiomatic vulgar colloquial dismissal English) go away! vb. 1 (context idiomatic intransitive vulgar colloquial UK Canada English) To leave, to go away. (from mid-20th c.) 2 (context idiomatic transitive vulgar colloquial English) To annoy, anger

Usage examples of "piss off".

If you piss off the owner, you are going to be head down in shit, deeply head down in shit, faster than you can say 'Condom.