My SO and I were at a friend's house on the weekend and were enjoying quite a few drinks. When we asked what she was up to the next weekend she mentioned that she was busy. My SO kept pressing to find out her plans as she thought that our friend had finally met a new guy.

Our friend let it slip that she was going to be attending a large orgy and that she had been going to them for quite some time. She told my SO that we were welcome to tag along.

My SO laughed the whole thing off while we were there and told our friend she was crazy, but in a good way.

Since then my SO brought up the whole incident. We talked and talked and talked and she's not against the idea, but isn't sure it's for her. We've played about with some soft threesomes and I had a drunken foursome without her once, but neither one of us has ever had any experience with a full-blown orgy and she's the only person we've met that has ever admitted to going.

How many people go to these? Are they really all that common? What kinds of things should we expect if we do end up going?

That's the biggest thing blocking my SO: that we don't know what to expect.