I just want to say that we (including me) should stay away from the opposite sex as much as we can. Just because you can't PM someone from the opposite sex doesn't mean all is well and just because you are talking infront of the whole world doesn't make it Halal Either. Idle chit chat and joking between sexes is as haram on SF as it is anywhere else. I just want to request people to stay away. Just like one brother has started dreaming about SF trolls, one can also dream about members of the opposite gender. And also, jazakAllah sister, JazakAllah brother is also in the grey area. And dear brother, dear sister is also in the grey area.