This phrase is universally used in all countries when speaking English. It is also the standard term for the fixture you go pee-pee in or poo-poo in. However, in Ireland, UK, Australia, and Singapore, it seems toilet is also used for the room the defecator lies in, while in USA at least, it is only used for portable toilets, toilet cubicles, and sometimes the term "public toilet" when outdoors, though never as a term for the entire washroom itself.

So, how does this phrase sound to people living in those 4 countries when it could either mean you need to go poo-poo or pee-pee or that you could just need to enter the loo? What if you are going to wash your hands? Do you say "I am going to wash my hands in the toilet"?

I know Britain has euphenisms such as loo, water closet, and lavatory, while Ireland has loo.

In Australia, many use bathroom, and I heard from my sister-in-law, it is the same in New Zealand and even in Singapore when she and her husband were transiting in Singapore Airport.

In Canada, standard terms are either washroom or bathroom, while in USA, it is either bathroom or restroom, though lavatory is used only in flight announcements.

In USA and Canada, you would really use this phrase only if you needed to actually use the appliance.