This very exclusive anti-Greek-philosopher group's motto was "Invent Yourself!" To join the group, all individuals had to agree that there is not any one ideal (sign and have paperwork notarized, please), so take that, Plato. These guys began every meeting by chanting "Man makes himself through his own choices and decisions! Man makes himself through his own choices and decisions!" while staring at himself in a pristinely polished mirror. This group rejected its philosophical forefathers' belief that there is one way to go. In fact, "individual-ins" took place with people talking about how different they were from one another, often arguing, but usually agreeing. Toward the end, the meetings started to resemble culty seminars, so the group dissolved.
Simone always made sure that everyone agreed that they were individuals, mainly because she didn't want Sartre to get all riled up and have to endure another lecture. She often threw out random test questions, such as "Is an alcoholic better than a king? Anyone?" Um, maybe?
Aron was vital to the organization, keeping members in check and making sure that they understood exceptions, like the fact that all these people have jobs and responsibilities (but they're still free). Such reminders often led to chanting, swaying, guitar playing, and lighters being held aloft.
Everyone knew that a lot of Sartre's ideas were "inspired" by Heidegger, so they decided to make him the mascot. (Someone proposed "muse," but Sartre thought it was too feminine, too "second sexy.") Anyway, it all got ugly when Heidegger said he wouldn't put on the furry costume and skip around unless Sartre admitted that he was wrong about the whole "existence precedes essence" thing and that he was trapped in a form of metaphysical thinking meant he would never get at the truth of Being. Yeah, it got awkward.