Most of you probably already know this, but generally, being "pissed" is a good thing in England. Well, that is to say, "Pissed" and not "pissed off," that meaning still holds true over here, but they're two separate definitions. Pissed means drunk, to a degree, generally with a positive connotation (although it might depend on the circumstances-- if you were "so pissed last night that you ended up in Trafalgar square with no clothes on," then generally that's a little too pissed... obviously).

And a few, related sub-definitions:

Piss up. Primarily a party where lots of drinking is going to be going on. "We're out for a piss up tonight."

On the piss. As in, "Going out on the piss," means to head out with the intention to get tipsy.

Piss-take. Now, this one's a little different. Generally refers to a making fun of someone or a practical joke of some kind, as in the verb taking the piss: "Are you taking the piss?" (which the American equivalent is "Are you pulling my leg?"). Used as a noun, it becomes piss-take, as in "I came outside and my car was missing. At first I thought it was a piss-take."

Me, during a night out on the piss in Brugges: