This reminds me of the classic Milgram study on social conformity. In this study, Milgram had "confederates" stop on a busy city street and look upwards at the sky. He demonstrated that when one person was looking up, 40 percent of passerby also looked up, just in case something interesting was happening. (There was nothing to look at, just sky and buildings.) When two people were looking up, 60 of passerby looked up. When there were three people, the percentage jumped to 65 percent, and when there were four people nearly 80 of strangers stopped and stared upwards.
This dance worked the same way. At a certain point, the group of awkward dancers becomes undeniable - they can no longer be ignored. And that is when the contagion begins. Once we start to wonder whether the dance is fun - or what that cluster of people is looking at - then it's only a matter of time before we too start to dance. Jane Jacobs, in other words, was right: "Life attracts life".
Here's the video--watch til the end: