I remember a boss of mine early in my career mentioned he was going to go powder his nose. Maybe in part because he is gay, but I found that endearing.
I have thought before that the long list of ways you can describe going to the bathroom to be amusing, and likely challenging for someone learning English. In French you just need to learn « aller aux toilettes » and that will serve you in almost all situations. « Aller au petit coin » (“go to the little corner”) is definitely more slang-y and not something a tourist is likely to encounter.
On the other hand, to where to go in English you may need to know “bathroom, toilet, restroom, loo, WC, washroom, little girls’/boys’ room, ladies’ room” depending on where you are.