powder your nose
powder (one's) nose
A polite expression used, usually by women, when excusing oneself to the restroom. I'll join you at the table in a minute, I just need to powder my nose.
powder your nose(of a woman) go to the lavatory.
This is an early 20th-century euphemism, which is now rather dated. The term powder room has been used since the 1940s to refer to a ladies' toilet in a hotel, restaurant, or similar public building.
1972 L. P. Davies What Did I Do Tomorrow? I'll use your bathroom. To powder my nose, as nice girls say.