It means both UK/Europe : pissed meaning drunk is more likely, but we're absorbing and using Americanisms too, so you need more context. USA : meaning mad or angry is much more likely

"To get drunk". To get mad is "to get pissed off".

I'm English and usually use TO GET PISSED to mean to get DRUNK. I usually add the OFF to PISSED when I mean ANGRY. TO GET PISSED OFF. But there is no confusion even without the 'off' as context will give you the meaning, and I'm used to Americans using 'pissed' to mean angry.

It is like When you stay upset..."Você fica chateado com algo" ou você fica aborrecido com algo".

to be pissed or to get pissed = to be drunk, because when you are drunk you need to empty your bladder very often and often you wet yourself when drunk. "to be pissed" or to" be pissed off" = to be angry or "to be mad" is another expression.