Group sex (or orgy), seemingly in fashion at the moment, has always had its adherents. In sex, as in most other things, there's nothing new under the sun.

The largest number of group-sex participants almost certainly figured in religious orgies where literally hundreds of half-crazed individuals could desport themselves in abandoned fashion. In the words of John Atkins in "Sex in Literature", "Mass copulation has always had its devotees, sometimes for the most admirable of reasons." The Bogomils and Fraticelli used to practise sexual promiscuity for the greater glory of God (though they probably enjoyed it themselves as well).