humorous if a woman says she is going to powder her nose, she means she is going to go to the toilet.
Well, if you'll excuse me a moment, I'm going to powder my nose.
powder (one's) nose
euphemism To go to the bathroom. The phrase is a polite expression used to excuse oneself when going to the bathroom. Typically used by women. I'll join you at the table in a minute, I just need to powder my nose.
powder one's nose
and powder one's face
to depart to the bathroom. (Usually said by women, or jocularly by men.) Excuse me, I have to powder my nose.She just went out to powder her face.