BEE AGGRESSIVE Cushion combatants come out swinging in Union Square.

Photograph: Paul Hardwick/Flickr: Macronin47

Feathers will be flying in Union Square on Saturday 22, but not because of any pigeon turf war: It’s International Pillow Fight Day, and the urban arts collective Newmindspace (newmindspace.com) is coordinating a sleepover-style battle royal in New York, L.A., Paris and more than a dozen other cities around the world.

The group’s founders, 21-year-old University of Toronto art students Kevin Bracken and Lori Kufner, are on a mission to turn city sidewalks into grown-up playgrounds. “We’re trying to bring awareness to public spaces. We refer to parks as ‘fun ghettos’ because they’re the only places where [you’re] supposed to gather,” says Kufner. “Nobody thinks of sidewalks that way.”

The first Newmindspace event took place in Toronto over Easter weekend 2005, when nearly 150 participants scoured Yonge Street in search of thousands of plastic eggs. (The brightly colored ova contained upbeat messages like THERE'S LIFE OUTSIDE and SUNNY SIDE UP.) Since then, the pair, who have been dating for three-plus years, have orchestrated lightsaber battles that attract legions of Darth Vaders and Luke Skywalkers, as well as massive capture-the-flag games on both sides of the border. (A bubble-blowing event is scheduled at Astor Place in June.)

Though their events draw large crowds in both in New York and Toronto, there are noticeable differences between the two populations. “In Toronto, the participants are younger and a lot of them are part of the dance-music scene,” says Bracken. “New York attracts more artists.”

Alongside local instigators like Improv Everywhere and the Danger (who staged the One Night of Fire march across the Brooklyn Bridge), Newmindspace is part of the “senseless culture” movement that’s invaded urban areas in recent years­—groups staging large-scale but fairly agenda-free happenings in public places. But Bracken says his group strikes a slightly different chord: “When people see Improv Everywhere pull a prank, it elicits a chuckle. When they see one of our pillow fights or bubble battles, there’s an earnest kind of euphoria.”

While such public spectacles require prudent planning (Saturday’s pillow fight begins with a whistle-blow at precisely 3pm), you can’t always predict how things will play out. “At our last game of capture the flag in Brooklyn, a cop rolled up out of nowhere,” Bracken recalls. “He says, ‘Hey, Red Team, Yellow Team’s givin’ us 50 bucks to arrest all you guys so they can get the flag! Whaddya you got for us?’ ”

Newmindspace celebrates International Pillow Fight Day Mar 22, 2008, in Union Square.