Brookfield -- "A lot of teenagers run around naked when they're playing the game," Sam Davel said.
That explains why Brookfield Police received calls about naked teenagers running through people's backyards earlier this month.
"I'm very surprised," Elsie Gessay said.
Brookfield Police aren't.
"That's one of the rules, you're not out if you get hit when you're naked," Davel said.
Police say this has been going on for years. Former Brookfield Central students agree.
"It's pretty much a school tradition," Danny Harrigan said.
So much so it's in the school yearbook - with a two-page spread.
"You get a team of five people," Harrigan said. "From there you just try to coordinate everything and be the last people standing."
To possibly win a cash prize.
"For our classmates, it's pretty much a given thing. Almost everyone in the senior class did it," Harrigan said.
The yearbook describes the rules. It also has a picture of a naked teen toting his nerf gun. And shows you what should be in your arsenal.
"For us and for me especially it was just harmless fun. We didn't go out and try to cause a disturbance," Harrigan insists.
But others think it's gone too far...Especially the nudity.
"They should behave and respect everybody's property," Elsie Gessay, who's lived in Brookfield for 60 years, said. "If they have parents, parents should be more involved with them also."
"I think for the community to see people running around naked, that's a bit of a surprise to people," Harrigan said. "But I think it's just a way for us as we're like growing up to try to find ways to express ourselves and try to be rebellious."
Brookfield Police sent a letter to Brookfield East High School parents warning them about this behavior.