This prank reminds me of that Stanley Milgram experiment where people stopped on busy New York City sidewalks and looked up. When only one person was stopped, about 4 percent of pedestrians joined the man and looked at whatever he was looking at. But as Milgram increased the crowd size, more and more people stopped and stared. In other words, it was a positive feedback loop. A bigger crowd staring at the sky led to even bigger crowds. And everybody was looking at nothing.* Such is the power of “social validation”.
*I like to pretend that this psychological phenomenon explains American Idol.