I most recently heard this in the context of a business deal:
Sorry gents, looks like we'll be taking the piss on that one.
I understood that the business had suffered a financial loss, although I expected I was missing some nuance.
In entirely different scenarios, I've heard piss used in British idiomatic phrasing that suggested a lack of concern, or carelessness. Those phrases are difficult to reconcile with the previously mentioned usage. Are there multiple idiomatic meanings for this word, or am I missing some kind of unifying theme?
Updated: I might not have a perfect recollection of the quote. But given the typical meaning of the phrase, I wonder if the speaker's intention was along the lines of "We'll be laughing about this later." Or maybe I just missed the real meaning.