When the city of Milwaukee held its annual pride parade on June 11, marchers turned up with all the usual paraphernalia like leis, feather boas, balloons and, of course, rainbow flags—there were thousands of those. But a new flag also turned up this year, and it’s been getting its share of buzz.

Actually, it was a really old flag—the Wisconsin state flag, to be precise—but with a very new twist.

The 1848 original flag shows a miner and a sailor supporting the Badger State’s shield. But the version of the flag that popped up at Milwaukee’s pride event showed the hitherto unknown reverse side of the flag, the one that shows that the two men are actually holding hands behind that shield.

Of course, that isn’t what the state’s founding fathers had in mind when they drew up the logo 169 years ago. But, as it turns out, it’s what Sean Burns has had on his mind for a while now.

Burns is the executive creative director of ad shop VML’s Chicago office, which designed the gay version of the flag pro bono for the ACLU of Wisconsin. The Wisconsin-born Burns had the state flag up on his wall for years. And every day, he would absentmindedly stare at that miner and that sailor. Then one day, he said, it just hit him: “Wouldn’t it be cool if they were gay and holding hands behind the shield?”

Burns was also a longtime member of the ACLU. (“That idea and my appreciation for the ACLU met in a bit of kismet,” he said.) He knew that the organization participated in the gay pride parades in his home state, so he decided to offer his gay flag to the Wisconsin state chapter.

Which is how Kristin Hansen, development director of the ACLU of Wisconsin, received one of the stranger emails of her career, one she actually thought was a joke until Burns explained the purity of his intentions.

“We just loved it,” Hansen said. “It was a little sassy and irreverent.”

Oddly enough, Hansen was concerned that riffing on the Wisconsin state flag might not be legal, fears that were assuaged when the ACLU office’s legal director gave her the green light. With an assist from VML, Hansen created hundreds of 3-by-5-inch flags and shipped them to Milwaukee.

And the response?

“It’s working just the way I wanted it to,” said Hansen, who explained that it generally takes people a few seconds to get the humor of the thing. “People look at the front say go, ‘So…?’ And then they turn it around and take a second look and [say], ‘Oh, my God!'”

Hansen’s staff gave the flags away at the Milwaukee parade and plans to do the same at the Madison, Wis., march in August. Her employees went to Milwaukee wearing T-shirts with the flag emblazoned on them. The shirts were so popular that Hansen is currently pondering the idea of selling them to the public.

The flag has also gotten its share of pickup on Facebook, via the Wisconsin Gazette and everyday fans. But the biggest measure of the flag’s impact might just be the lack of any real criticism. “We haven’t had a single negative comment,” Hansen said. “The response has been joyful. People just really think it’s fun.”

And that’s good enough ROI for Burns.

“I always like doing pro-bono work for … organizations I believe I can get more emotionally involved in,” he said, and the ACLU is one of those. “They take your side, and sometimes, they take the side you’re not on,” he said. “But it’s still super important work, and I appreciate their being guardians of what we all deserve—the whole liberty bit.”