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
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.