Two 90 year olds had been dating for a while, when the man told the woman, "Well, tonight's the night we have sex!"
And so they did.
As they are lying in bed afterward, the man thinks to himself, "My God, if I knew she was a virgin, I would have been much more gentle with her!"
And the woman was thinking to herself, "My God, if I knew the old geezer could actually get it up, I would have taken off my panty hose!"