urinating, emptying one's bladder.

In England the term pissing means to go bar hopping, which I believe is how we began to use it to mean "urinating"

Listen to the lyrics from ChumbaWambas Song 'Tubthumping' they are refering to bar hopping.

"I get knocked down
But I get up again
You’re never going to
Keep me down

Pissing the night away
Pissing the night away"

Similar to bitching. Comparable to the excritment of waste.

instead of using "pissing"
round walsall u might hear the phrase ..piziling - the slang word meaning "pissing"