"Pissed" vs "Pissed off"
In Australian English there has always been a distinction between "pissed" (intoxicated) and "pissed off" (angry, irritated).
I've noticed a trend towards the American usage where "he was really pissed" is now much more likely to mean the latter.
I'm aware of the futility of resisting the natural evolution of language, particulary the juggernaut of American language imperialism via films and TV, but it seems a shame that "I did it because I was pissed" is now ambiguous.
Is this a trend in other English speaking countries where the Australian usage was common?
Harold Wentworth & Stuart Flexner, Dictionary of American Slang, first edition (1960) has this entry for pissed off:
pissed off {taboo} Angry; enraged; disgusted; completely and thoroughly exhausted; fed up; unhappy; forlorn. One of several such terms very widely used by Armed Forces in W.W.II and carried into civilian life afterward. Though still taboo, this term has passed into sophisticated use among the culturally elite or pseudo-elite.
This edition of Wentworth & Flexner has no entry for pissed in the sense of drunk.
Robert Chapman & Barbara Kipfer, Dictionary of American Slang, third edition (1995) shows some evolution in the variant wordings used:
pissed off adj phr (Variations: pissed or p'd or peed off or po'd) Angry; profoundly annoyed; indignant: [examples omitted]
This edition of Chapman & Kipfer has no entry for pissed in the sense of drunk, either.
I remember that people began shortening pissed off to pissed (still with the meaning "angry") during the middle 1970s, because I had a roommate in college at that time who used to counsel anyone who confessed to being "pissed off" that "It's better to be pissed off than pissed on." He told me that the truncated form pissed had ruined the fine edge of his wise saying.
On the other side of the Atlantic, Eric Partridge, Dictionary of Slang and Unconventional English, first edition (1937) reports a very different meaning of piss off:
piss off. To depart, esp. to depart quickly : low : late C. 19–20.
And for "pissed," the same edition of Partridge has this:
pissed or pissed-up. (Very) drunk : low, and military : C. 20.
As of the fifth edition of Partridge (1961), the dictionary still had no entry for pissed or pissed off in the sense of "angry." However the eighth edition (1984) has these additions:
piss off, v.i. To depart, esp. to depart quickly (often as an imperative: piss off!, go away!): low: late C.19–20. ... —2. V.t. To irritate, annoy, often with connotation of either malaise or disgust: since late 1940s. [Example omitted.] Hence pissed off.
...
pissed off. Disgruntled, 'fed up'; very much displeased (with someone or something): since late 1940s, Services; in 1970s very common among students.
It thus appears that U.S. English slang and British English slang ran on separate tracks for a long time, but that both now acknowledge and use the "angry" sense of pissed off. Further, I'm quite familiar (conversationally) with pissed in the sense of "drunk," so that meaning of the term must have become at least somewhat naturalized in parts of the United States in the past two decades.
In Australian English there has always been a distinction between "pissed" (intoxicated) and "pissed off" (angry, irritated).
This is exactly the same as the British usage.
I've noticed a trend towards the American usage where "he was really pissed" is now much more likely to mean the latter.
I have not noticed that in the UK.
Being an American, I can safely say that both are used quite often to mean the same thing: angry or irritated. "I was so pissed when he spilled coffee on my new sweater" or "it really pisses me off when she talks down to me" would be understood in America as the speaker being angry. As far as I know, we never use pissed or pissed off to mean intoxicated.
Also, it is not common to use the imperative/insult (?) piss off in America, but if you were to use it you would be quite well-understood. :)
In New Zealand, that distinction still exists quite strongly. But, like you, I have heard a few people use "pissed" to mean annoyed, but the vast majority of the time, I have only heard it in the sense of being intoxicated.
I wouldn't worry too much about it though. There are so many words in English that mean "drunk" that it wouldn't cause too much to be lost. But yes, it is a little bit of a shame. But, we cannot stop the juggernaut that is the progression (for good or for bad) of the English language.