Short version
It's having more than one reletionship going on at once, with all people involved knowing and consenting.

In my case, I'm a girl with two boyfriends all living together, or in my other third's cases, they're boys with both a boyfriend and a girlfriend. Some people I know have seperate partners, who they divide their time with... never seen that one work out though.
(stimpy, Wed 30 Sep 2009, 21:18, 2 replies, latest was 16 years ago)

actually I wouldn't be classified in this
as I'm quite single

to be honest, I now believe you are a porn star
( Lisette von Falcon, Wed 30 Sep 2009, 21:27, Reply)

I like to believe every woman on the internet is a porn star
It's the only thing that keeps me coming back.
(Bazongaloid, Wed 30 Sep 2009, 21:29, Reply)

Ahh, yes
We all are, really. Would you like to see my silicone enhanced EE's?
(stimpy, Wed 30 Sep 2009, 21:34, Reply)

I thought up until now you were a man
That is all.
(The Apeface Cherub is not a cunty-uber-cunt, Thu 1 Oct 2009, 6:21, Reply)