That's mostly me. I might be uncomfortable with talking about sex if a friend is talking about his or her intimate relations with another person, due to the fact I don't know if the other person knows he or she is being talked about. But it wouldn't bother me to hear about sexual details if both people in the relationship were comfortable with it. It did piss me off that one of my supervisors started discussing one of my coworker's sexual relations with his girlfriend (who happened to be best friends with my supervisor) because neither my coworker nor his girlfriend knew that they were being talked about in that manner.I, personally, have nothing against talking about sex.
Yeah, I'm similar. The internet is *not* a medical office. And yeah, it's private matter. That's why I tend not to talk about sex in public, and if I must, I keep details to a minimum.I talk about sex with those it's... er. "Relevant" to, let's say. Also, doctors.
Aside from that, I'd rather not, and it makes me uncomfortable when friends/acquaintances hit me with the details of their sex lives. I don't want to hear anything of the sort from my family members, either. It seems too private of an act to share that way.