When the conversation starts to wane, I usually bring up sex stuff to get it going again. I'll usually just mention something sex related I saw in a movie/tv show we both saw then ask if that's normal, then ask if she likes it, then what she likes, etc.

Girls are usually playfully taken aback at first but then slowly open up a lot and it gives us a ton to talk about.

Is this a good topic to talk about with a girl you're interested in? I figure it either A) makes them start thinking of you as a sexual figure (good) or B) makes them start thinking of you as a playful friend they can gossip about sex with (bad)