Tango.

Michael Crowe wrote a letter, enveloped it, and left it for strangers: 

It compelled people, strangers, to be on the steps of the V&A at a specified time and date, holding two oranges. 

He'd be there to meet them, exactly a minute after the specified time.

No small talk, no greeting. Just a mutual recognition, aided by both holding oranges. 

After 10 seconds, he would drop the oranges, take his camera, and photograph the strangers; capturing their confusion/amusement/beauty.

There was a secret in his formula. 

When he dropped his oranges, they'd float to the sky. They were actually two small, orange, helium balloons. 

Here are his results:

Pretty rad guy. Go see his ideas at fig crumbs.