Someone you hang out with and are friends with only because they are really good friends with someone you want to date or plow, and when you hang out with them, they're likely to invite the hot person.
Keith: I hear your hanging out with Larengo tomorrow. I thought you hated that Farkleberry?
Henry: no, I'm only doin it so I can meet that chick, Latrice. He's my middle man.
When you post a status on Facebook, asking people something or just a status you know will generate a lot of comments and the first person to comment on it is the person nobody likes and you aren't sure why you're friends with them, but they write some dumb comment and then nobody else wants to comment because it's all fucked up by the person, trapping you in a social condom.
Keith: hey is anyone going up to the mountain friday?
Curtis: I am! Hope I see you there!!! :)
Keith (thinking): wow just great. Now I'm trapped in a social condom!