I love things like this. I was a theater major in college, and one of the subjects I took was Experimental Theater. One topic in that class was on "happenings." Basically, a happening is when a group of performers get together in public and create a performance amidst a crowd who doesn't know what is going on. They are usually a lot of fun, and you can get some of the truest emotional reactions from people. I think we need more happenings in America.
(Hat Tip: Andrew)