When the Chicago Bears face off against the Green Bay Packers at Soldier Field on Sunday, Bears fans will finally have an answer to their rivals' famous foam headwear.

The "Graterhead" — a Bears fan-designed cheese grater-shaped hat and the latest craze in Packer Cheesehead-hater fashion — made its debut when the Bears played the Packers at Green Bay's Lambeau Field on Nov. 4.

Minnesota Vikings fans can say what they will about their rivalry with the Packers, but inventor Jeran Dahlquist said about 90 percent of the couple of thousand Graterheads sold since have gone to Bears fans.

"I don't think anyone hates the Packers quite like Bears fans," said Dahlquist, of Boise, Idaho.

Dahlquist, a graphic designer and self-described Bears fanatic with "kind of a different sense of humor," came up with the Graterhead as a way to one-up Packer supporters by turning their iconic symbol against them.

He spent a week cobbling together the first prototype about three years ago, using supplies from a local craft store, he said. Silver-painted fake fingernails mimicked a grater's cheese-shredding bumps.

Early test runs in Boise Packers bars convinced him he was onto something. After working with a Midwest manufacturer to create a foam, fingernail-free version, Dahlquist and business partners Seth Neal and Dean Donlon introduced the Graterhead at the first Bears-Packers game of the regular season. Their marketing plan was simple — splurge on 11th row, 50-yard-line seats, cheer like crazy and hope the TV cameras noticed — and it worked, Dahlquist said.

They sold 500 Graterheads that day, despite a website that struggled to keep up with the flood of traffic, Dahlquist said, and drove to Chicago for a series of interviews. While there, he stopped at Mike Ditka's restaurant to drop off a Graterhead for the former Bears player and coach.

"He came over to the bar, patted me on the back and said, 'I think you've really got something here,'" Dahlquist said. Ditka wore the Graterhead during his weekly ESPN radio show the next day.

The Graterhead — available online at graterhead.com and in limited numbers at the Official Chicago Bears Pro Shop at Soldier Field on Sunday — is just one of the ways fans can wear their Packer disdain. Online vendors offer anti-Packer T-shirts, bumper stickers mocking former Packers quarterback Brett Favre, even "No Cheeseheads!" wine charms.

Kevin Doolan, who designs and sells Chicago sports T-shirts at cubbytees.com, said he's found that fans generally prefer slogans supporting teams they like to those mocking teams they don't, unless it's a particularly clever idea.

Doolan still makes a couple of anti-Packer shirts but said most are shipped to Wisconsin addresses. He suspects his customers are former Chicagoans sticking up for their team behind enemy lines, he said.

Joe Sienkiewicz, of Carol Stream, owner of chicagosportsshirts.com, another site selling T-shirts for Chicago fans, said his anti-Packers shirts have replaced those mocking the Cubs and White Sox as his best-selling rivalry gear. After hearing about the Graterhead, Sienkiewicz designed a T-shirt version with a cheese grater on a navy background, for Bears fans, and on a purple background for Vikings fans.

Sienkiewicz said the Bears' record this season is probably helping all anti-Packer sales.

"When you're ahead, then you can brag," he said.

Dahlquist said there may be more Graterhead items on the way, but don't expect him to branch out to other teams.

"It would have to be Bears-centric," he said. "I can't imagine working on something all day, every day that I didn't have a passion for."

lzumbach@tribune.com

Twitter @laurenzumbach