For me, it's social dancing, specifically West Coast Swing. Because while there is just social dancing, and some who only do it, there's a bit of a culture of competition, and it has its own governing body for determining where you place in competitions, and when it does sound like a cult when described.
A friend of mine got obsessed with KGATLW and he would seriously evangelize about it every chance he'd get.
Tbh, fair, because King Gizz rocks hard as shit, and they have something for almost anyone.