Ebbie, certain practicalities make life easier for users of euphemisms. In most European and American public space, hand-washing facilities are always found near the toilets, so if you can't bring yourself to say "toilet" you can find one by asking to do something much more socially mentionable, i.e., wash your hands. In private homes, people don't really want you at the kitchen sink or in the laundry room, so they will likewise direct you to the bathroom, the only other place with running water and plumbing.

I love the genteel way Americans ask if I want to use the loo. "Would you like to freshen up before dinner?" It's so sweet.