In the US, it would mean to appear to be upset, and in the UK, it would mean to appear to be drunk.

It has two (informal) usages: 1. You could say somone is "pissed", to mean the person has consumed too much alcohol and is drunk. I would usually say someone is "pissed" if they are very drunk. Example: They are so pissed they can't stand up! 2. You could use "pissed"/ "pissed off" to describe a person's emotions. If someone is angry/ annoyed about someone / something. This tends to have negative connotations. Example: He is pissed off at me, because I forgot his birthday.

I agree with James - it depends who is saying this. If the speaker is using British English, it means that they have the impression that the other person is drunk. If they are using American English, it means that they think the other person is annoyed about something. Note that this is a informal term, and, in the case of the British usage, fairly vulgar.

I figure that means anger or annoyed.

To seem to be angry about something.