When we speak English, should we say WC and toilet when we want to go to the bathroom?
People may understand your English, BUT, they are not the best English words to use. Other words sound nicer and more professional.
Also, in the USA, many people may not know what "WC" means.
Instead, when speaking English about the bathroom,
let’s try… Excuse me, where is the …………?
1. restroom
2. men’s room
3. ladies’ room
4. washroom
5. lavatory
6. bathroom
Even though people will understand your English, it is a good idea to know a more polite, professional, and nicer sounding way to say certain words to strangers or at work.