There is 4 of us girls in my close friend group and 3 of us have boyfriends. My best friends' boyfriend has been kind of flirting with us other 3 right in front of my friend. To start with it was just a joke and we all played along, then he started asking stuff like "if we both weren't in relationships, would you have sex with me" and say things like "your hot, can you keep me warm tonight" to our faces, over skype and Facebook, and it's all just getting out of control. We girls are getting sick of it and it's really starting to upset our boyfriends and my friend, but he's fun to hang out and joke around with.

What should we do?

Are you flirting back? You guys might have given him permission to act like that unwittingly by joking, flirting right along with him. Now that he's taken it to Creepville, you have to put those boundaries back that weren't there in the first place. Say, "You joke like that a lot and it is now making us uncomfortable, please stop." If you're unwilling to do that or enjoying the attention he'll keep doing it. As an aside, sounds like this guy is not into your friend... or is at least into having sex with other people and looking for some kind of "outside" situation. For the sake of your friendship, extract yourselves now!

All you girls, and your boyfriends need to tell him to stop.