Years past, now about 6 years, dc had wnbr (world naked bike ride), and as a capital of the supposedly free world, art lovers, bike lovers and just some different is not deficient bikers and media plus gawkers seemed to show up.
Iirc from some backup paperwork handed me, a permit might be required for use of a park for setup (read dress down and media time) then almost CritMass like wandering the streets along the probably legally prescribed parade like route, while police and others hassle you to stay single file, just because, etc...
Around art galleries were the kewlest, the white house and capital mixed results, but stops for photo ops.
That said legal and other advocates may consider the startup opportunities and legal and social promises of that type of advocacy. Being now very warm outside, even without threats of global warming, and Chicago and other places having their acts together, I'd be remiss not to mention it. Someone could even go as a lame duck, cough.
Nsfw? Idk, ianal (I am not a lawyer)
http://wiki.worldnakedbikeride.org/index.php?title=Washington,_DC
But you were not left out of the loop...