[AN: First link leads to a video in which Musicians keep turning up to join in playing Beethoven's 9th, or Ode to Joy. There's even a Chorus. Second video features a dance performance that becomes a proposal.]
Art has many facets. There's even a form of art that aims to have the viewer question, "What is art?" Of the performance artists, there are more many and varied types than one might imagine. Which includes the Flash Mob. A group of individuals with nominal co-ordination who agree to do a public performance of something with little notice and the tools on hand.
All they needed was the ability, the time, and the tools. Convenience of transit to get to the site of the scene should have been, but it's amazing the lengths that Humans will go to in order to create weirdness. Anywhere that population might be available to view a live performance, Humans will make surrealism for everyone else.
For example, Passalong Station. A nexus in which the motto is Hurry Up And Wait. Those who work there gain entertainment from sharing Weird Customer Stories. The work is almost monotonous, save for that. At the end of a term, they fly home to the nearby planet and take some extended time in which routine is no longer necessary.