National Nude Day
Yes July 14th is national nude day and here is how it got started from an article on website "thereisadayforthat":
"National Nude Day" began as a spoof public holiday in New Zealand when TV personality and former rugby player Marc Ellis challenged viewers of the TV2 talk show SportsCafe to streak in front of then Prime Minister Helen Clark.The show ran an event each year inviting viewers to submit photos and video of themselves performing daily activities in the nude, which was continued on the internet (rebranded as "World Nude Day" or "International Nude Day") until around 2009. July 14th has become the accepted date of the day, but the date was never formally agreed and was sometimes held in September or February.
The holiday has evolved to become a worldwide celebration of naturism.
Yes, WNBR has rules. I'm sure they vary by location, but here there is no nudity allowed before or after the ride, or anywhere away from the route. They are becoming more lenient with after-party nudity, though the official rules remain.