I feel it depends on who is asking the questions and why. If it is a doctor; fine. Boyfriend-ok he has a slight right to know somethings. Your neighbor-- total embarassment and will make anyone extremely uncomfortable.
I am comfortable with it for the most part but of course get uncomfortable/shy in some instances. As said by others it depends on your background. It is technically "unladylike" to talk about sex in an open setting.