1.
If someone or something pisses you off , they annoy you. ( INFORMAL, RUDE )
It pisses me off when they start moaning about going to war.
PHRASAL VERB : V n P
• pissed off
I was really pissed off.
ADJ
2.
If someone tells a person to piss off , they are telling the person in a rude way to go away. ( BRIT INFORMAL, RUDE )
PHRASAL VERB : V P