Intoxicated, inebriated, drunk, under the influence of
alcohol.
It is sometimes used to denote ire or anger, but when it is it is usually always said 'pissed off'.
According to some sources the origins of 'pissed' derive from the practices of
pagan northern european peoples imbibing the urine of others (primarily shamen) who had ingested the Amanita Muscaria
mushroom to obtain its active compounds.