Never happened. The first and only time it was offered was by a girl I was fukking on and off for a few years back on my birthday in 2014. She was at a nearby bar and wanted to bring a friend of hers I knew to my place to give me a threesome as a birthday gift. I agreed but one or both chickened out and they didn't end up coming over. But luckily another girl I knew came over to make up for that anti-climax.
3.5 years later while the girl I was fukking went to work overseas, I fukked that friend a couple of times at my house. Learnt from that experience that when women talk about great dikk they have, their non-loyal friends will want a piece of that.