There’s a few I’ve heard, such as “Aunt Flo” and “Monthly Visitor”. Any other creative euphemisms you’ve used or heard? Interestingly enough, all-female band Tacocat has put together an entire song devoted to the subject. It’s actually quite catchy, if you can look past the subject-matter. “Communists in the Summer House” has to be one of the more imaginative phrases I’ve heard to describe it.