“You have the stereotypical New Yorkers on a television show or in a movie who are very gruff and short with people, but I don’t think that’s the case,” Todd says, speaking from experience. “Generally, if New Yorkers are given the opportunity to interact with something that’s funny, they will stop, they will take notice, they will enjoy it and they will interact with it positively. We did a project a couple years ago called High Five Escalator, where I had five actors line up along the stairwell next to these two giant escalators in the subway system holding up a sequence of signs that said, ‘Rob wants to give you a high-five. Get ready.’ And at the top there was a guy with a sign pointing to himself that said ‘Rob,’ and he had his hand out. I would say 90 percent-plus of the people given the opportunity to give a total stranger a high-five at 8:30 in the morning on the way to work in the middle of winter elected to do so. That surprised us a little.”

What sets Improv Everywhere apart from most well-known pranksters (think Punk’d and Jackass) is that no one is the butt of the joke. Instead of making someone look like the unwitting victim, they strive to give everyone — even those who are fooled — a positive experience.

“It’s easy to get a reaction in public by doing something that’s based in conflict,” says Todd. “Any two people can go out to a public place, pretend they don’t know each other and get into a fake fight, and you’ll have a crowd of people watching. But to me, that’s boring. I’m interested in seeing if we can make people stop and watch because something incredibly amazing is happening.”

Back in the park in Lower Manhattan, it’s clear that Todd’s latest MP3 Experiment has done just that. The sun has now set, and the two tribes have converged in the so-called neutral zone, halfway between both starting points. We quickly realize that even though the northern tribe is wearing white T-shirts, we have otherwise been following the same instructions that they have. After a variety of meet-and-greet activities (including a lightsaber battle with flashlights), we’re instructed to reach into our backpacks and retrieve one of the props we were told to bring: a glow stick. On cue, the crowd activates their glow sticks to begin a traditional rave dance. Following the rave is the flashing of the cameras, then the ­donning of masks and more flashlight action for a strobe dance party. We can sense the ridiculousness of what we are doing, but the overwhelming sense of freedom and joy of participating in ­something for the sheer fun of it is immeasurable. The omnipotent voice returns.

“Great job, everyone … take out your pen, bright objects and glow sticks. Make as much light as you possibly can for the finale of the dance. … It’s now time to say goodbye. When I say go, let’s all scream goodbye and point our lights up to the sky. Ready? One, two, three … .”

From Todd’s vantage point high above, a sea of people erupts into a field of blindingly beautiful moving lights. Mission accomplished.