I've attended and really enjoyed three gangbangs in my years in the lifestyle. Two of which were with the same couple and one of those was the first time I had met them. Even under those circumstances it went off pretty flawlessly. The secret was that the wife of the couple spent a lot of time talking to the guys before hand so it was less of an anonymous encounter. They invited five guys and got five to show up so it was six men altogether including the husband of the couple. By the time everyone actually showed up they all felt very comfortable with the couple. It didn't hurt that the wife of the couple is the wildest kinkiest woman I've ever met and we're still great friends.
I was coming in from out of town so I was the first to show up and even though we hadn't met in person, I arrived at their house and it felt like I was a family friend. The wife's mother stopped by to pick up the kids and I met them all, lol. After they left it was a mfm almost immediately after a couple drinks. We hung out, they smoked a bowl, I had another drink and then the other guys started showing up.
Jenn was amazing and into dp while sucking so at any given time, she was keeping three guys occupied. There were some performance issues so it was mainly left to three of us to do the fucking but it was a blast. All six did end up cumming on her and she was a mess but a happy mess.
I showered and stayed the night for another impromptu mfm in the morning before the kids were dropped off. We're still friends to this day and that was at least 6 years ago.