Where is the restroom?

use the restroom

1. To go to a bathroom, restroom, or toilet in order to urinate or defecate. Pardon me, for a moment. I have to use the restroom. Does anyone need to use the restroom before we hit the road? It's going to be a long drive to New Mexico!
2. euphemism To urinate or defecate, regardless of location. A: "What took you guys so long to reach the top of the mountain?" B: "Tommy had to use the restroom about halfway up the trail." I really wish people wouldn't let their dogs use the restroom on our lawn.
See also: restroom, use
Farlex Dictionary of Idioms.

Where is the restroom?

the appropriate way of asking for the toilet in a public place. Bob: 'Scuse me. Waiter: Yes, sir. Bob: Where is the restroom? Waiter: To your left, sir. Mary: Where is the restroom, please? Clerk: Behind the elevators, ma'am.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • restroom
  • use the restroom
  • use the toilet
  • use the bathroom
  • bathroom
  • go to the toilet
  • go to the bathroom
  • answer nature's call
  • throne room
  • little girls' room