“The powder room”. Or what do you call it?

Going to the toilet.
Having a wee.
Going to the loo.

dh will insist on saying "going for a sit down". A touch too graphic for my liking.

My Dad used to say, 'I'm off to see a man about a dog.'

I don't know why we have to announce this, but somehow, we always do. Is it because just getting up and walking out will be seen as ruder than saying, 'I'm going to the toilet?'
Here of course we say, 'Kei te haere au ki te wharepaku.'

Anyone who reads Lindsey Davis will know that the very first 'spending a penny' phrase came from the fact that Emperor Nero imposed a urine tax; later continued by Vespasian, a much hated move.

I remember putting the big copper pennies into the slot in public toilets, if no one held the door open for me as they were coming out!

www.ancient-origins.net/history-ancient-traditions/money-does-not-stink-urine-tax-ancient-rome-003408

Most in America say "go to the bathroom".

Going to the loo.

I say "going to the loo"

Point Percy at the porcelain is one I've heard

My mother in law used to say “spending a penny “

"Sending a friend to the coast" is my husband's saying.

My friend's husband says "I'm just going to shake hands with the unemployed" ?

Upper class terminology is lavatory. Check out Buckingham Palace signs if you doubt this.

I say 'I am going to the loo. My DM used to say she was 'going to make herself comfortable', if she made any comment at all. But whenever we were going anywhere, she would always ask before we left the house 'Have you all made yourselves comfortable?'

I don’t think there is any need to announce where you are going. A simple ‘Excuse me for a moment ‘ is sufficient.
I don’t like the expressions ‘going for a pee’ and going for a whaz‘ is even worse.
‘Point Percy at the porcelain ‘ ( males). Yeuk.

I go to the loo but send the grandchildren to do a wee!

We just go to the loo.

When he was going to be quite a while (sitting with the paper) my father used to say 'I am going to commune with my soul.'

I am going to use the facilities

Toodaloo

'I'm just going to the toilet' or 'excuse me for a minute' sometimes to family I say 'twilight'. ??

One term I do not use, but I believe common in the US is “rest room”
A lovely lady I knew who was once an Air Stewardess for BOAC , back in the day, was asked early in her career by an American passenger where “the rest room” was.
Unfamiliar with the term and thinking perhaps he wanted to sleep she replied that she didn’t think they had one on the plane, but “could offer him a pillow”
His face was a picture!

Loo!

Going to the loo is what I usually say. When I take the grandchildren out I say go and have a wee before we go. My nana used to say spend a penny

These days I think most people say going to the loo, but years ago it was spend a penny ( at school it was called going to the bogs!)?

I love the Lindsey Davis books BradfordLass and of course the urine tax was applied, the laundries used the urine for bleaching sheets and clothes.?

I don’t make an announcement but the words loo and lavatory are acceptable.

DH announces he is going to his 'ablutions' after breakfast or in short ' to ablute'!.