I was at 'sex parties' a few times in Switzerland, about 6 guys and the same number of girls, cocks hidden behind small towels until the real action started. The objective was to fuck as many of the girls as possible before you ran out of steam. All the guys turned out to be well endowed, a few more than me, so I do wonder if our lesser qualified friends are a bit reluctant to expose themselves to too much semi- public attention. It's not a scientific survey, just my impression. The only other times I've had 'group' sex was 2 girls and 2 guys; the other guy's cock was a little bigger erect but I wasn't concerned. I suppose if I'd been small I might have been. Anyway the girls didn't complain.