and Can I use your powder room?; May I use your powder room?; Where is your powder room?
Euph. a polite way to ask to use the bathroom in someone's home. (Alludes to a woman powdering her nose. Sometimes used jocularly by men. See also powder one's nose.) Mary: Oh, Sally, could I use your powder room? Sally: Of course. It's just off the kitchen, on the left.Tom: Nice place you've got here. Uh, where is your powder room? Beth: At the top of the stairs.