An elderly man and woman meet in a bar and get to talking. They are enjoying their conversation so much that, when the bar closes, they decide to continue at the woman's apartment.
After a time, things start getting pretty romantic and they wind up in bed. Afterward, they're both laying there, staring at the ceiling.
The old man is thinking, "Gosh, if I had known she was a virgin, I would have been more careful with her."
The old lady is thinking, "Geez, if I had known he could get it up, I would have taken off my panties."