Do you want to include live-action gaming into consideration.
I have, for example, been part of a line of people, doing the conga through a hotel mezzanine, carrying a sign saying "We are invisible". It was late night at a sci-fi convention, so not to many mundane folks to freak out, but still a bit out of the ordinary.
Another, live-action gaming oddity : in the middle of a shopping mall. A FLGS had organized game play at their store, but they didn't have space actually inside the store, so we played out in the common area among all the stores.