doesn't matter who the girl is(most of the time) you can talk to them about sex, they might say eww or whatever, but inside they won't really care and might even get curious.
well as long as that's not all you talk about then you should be fine.
for example, i was talkin to one of my friends (we'll call her "hi") and then i left to go kick it with my buddies. at the end of class, she's talking to my other friend (who is also named "hi"), so i go up to them, so what's happening? are you 2 going to have hot lesbian "hi" sex later?
they just laughed and said excuse me... keep in mind these are the so called "goody goody" girls
but i have actually been in a situation where the girl doesn't want to talk about sex, i thought she was weird. i started bringing it up and she just told me flat out to stop talking about it because it makes her feel weird. of course, that didn't make me stop so i kept going, but then she said it again so i changed the subject