1
general::
1. Make very angry, as in That letter pissed me off, or She was pissed off because no one had called her. [Vulgar slang; 1940s] 2. Go away, as in Piss off and stop bothering me. [Vulgar slang; mid-1900s]
American Heritage Idioms
2
general::
Phrase(s): piss someone off
Inf. to make someone angry. (Crude. Potentially offensive, even though it is widely used. Use with discretion.) • She really pissed me off! • That’s enough to piss off anybody.
McGrawhill's American Idioms And Phrasal Verbs