https://www.nme.com/news/music/paul-mccartney-masturbating-john-lennon-beatles-2377892
Speaking to GQ, McCartney spoke about an activity he previously revealed in his 1997 biography, Many Years From Now. “What it was, was over at John’s house, and it was just a group of us,” he explained. “And instead of just getting roaring drunk and partying – I don’t even know if we were staying over or anything – we were all just in these chairs, and the lights were out, and somebody started masturbating, so we all did.”
In the group were McCartney, Lennon, and three of Lennon’s friends, all of whom would shout out names as they were engaged in the masturbation session. “We were just, ‘Brigitte Bardot!’ ‘Whoo!’ and then everyone would thrash a bit more,” McCartney said.