Sex and the City did it glibly in season one, in the episode titled “Three’s a Crowd.” But no, surprisingly, it’s not Carrie Bradshaw (Sarah Jessica Parker) who comes up with the question, but Charlotte York (Kristin Davis), casually telling Carrie as they walk down the street, “How well do we ever know the people we sleep with?” Later in the episode, when Carrie finds out that Mr. Big (Chris Noth) was married before, she realizes, “Charlotte was right, we don’t really know the people we sleep with.”