I’ve been to a couple of Naked Bike rides. There is little to describe about what’s involved. You don’t have to sign up or anything. You just turn up at the starting point which is normally in a city park. Take off your clothes and put them in a rucksack and cycle round town. The only bizarre thing is simply taking your clothes of in a city park which will most likely have gathered the attention of many other clothed people who for some reason take their phones out and start taking photos!