World Naked Bike Ride (WNBR) is almost here! The event, which has taken place annually since 2004, involves many cities around the globe. A bit about the event and the mission from their wiki:

World Naked Bike Ride (WNBR) is being organized and supported by many different groups. The groups are only connected by their determination to all be naked on their bikes on WNBR Day, riding in celebration, jubilation to deliver a vision of a cleaner, safer, body-positive world to the masses. We have many great reasons to be celebrating, with all the glory of naked two-wheel sanity. It's time to join hundreds of naked compatriots in a free, non-sexual, fun bike ride!

If you’re in the Netherlands and you want to participate, keep an eye on the List of rides wiki for the Netherlands, located here. According to that page, the upcoming main Northern Hemisphere ride will be on Saturday 13 June 2009, so watch for potential Dutch cities where you can join the fun.