This has happened to me multiple times. I girl casually starts a sexual topic, because it fits naturally in the conversation, e.g. that she watches porn or that she has been a nude model in a pin-up calendar or that she had a wet dream with her BFF. So far I have tried to play it cool, as if it didn't affect me, but the past has taught me that my intuitive reaction is usually the worst one. I feel like I should dwell more on the topic and use it as a catalyst to get intimate with the girl, but I am unsure how. Any advice (on the given examples or other)?