In her stockings after the costume party. She went as a 1920s flapper. And to be historically accurate, she said, she didn't wear panties with her stockings.
I didn't know if that was, in fact, historically accurate. But I wasn't going to contradict her. So I told her if we we going to be historically accurate, we should have anal sex, since in the 1920s they didn't have the pill, and doing it in the butt was a common form of birth control.
That is only partly true, but she was in too good a mood to argue details.