Whats another way of saying that you need a wee?

I need to 'have a slash', 'point Percy at the porcelain', 'shake hands with the unemployed' 'have a gypsy's kiss'.
Then, after you have had too much to drink, there is the Pirate's P***. (You have to close one eye so that you can focus and hit the target properly.)
Something that we gentlemen frequently have to deal with is the Venus Pee Trap: that moment when you are in full stream and the toilet seat starts to fall down to its resting position.