The word pissed is used in the UK to signify drunk, whereas it means angry in the US. For angry, in the UK, we would use 'pissed off'.

In QC it depends upon the way you use it.

I got pissed on Saturday = drunk
I am so pissed (straight upset face) = angry
I am so pissed (goofy grin) = drunk
I am pissed off = angry

Piss off as an expletive means f**k off
Piss off as a verb means you made somebody angry

Piss off the bridge = guys showing off again