We all know the "Thinking Arby’s” TV campaign, where the Arby’s logo floats above the heads of various characters whose thoughts are supposed to be somewhere else. They've got an Arby's roast beef sandwich on their minds.

That ad got some creative sorts in Atlanta thinking how they could extend that message to an outdoor campaign for Arby's.

Here's what they came up with: balloons with the Arby's logo floating above characters in billboards having nothing to do with Arby's, such as an ad for a local TV weather person.

Without the balloon, she may have looked as though she was thinking of cloud formations. But the balloon changed the message completely. Our weatherman was really thinking about roast beef—and Arby’s.

The balloons appeared to be attached to the billboard but in fact were tethered to the ground nearby.

The balloons went up around dinnertime one day in mid September.

“The goal was to grab people’s attention in a guerrilla way, to catch consumers as they drove home while they were thinking of dinner,” says Jennifer Jones, vice president of public relations and social media strategy at Fletcher Martin, which came up with the idea.

“We were thinking of a fun way to get people’s attention, and it was also extremely cost-effective,” she says.

Because the balloons weren’t actually attached to the signs, the agency didn't need to get permission from the owners of the signs or the existing advertisers.

The stunt generated the desired effect. She says radio stations that evening were buzzing with people calling in about the campaign.

But the balloons were up only briefly.

“I don’t know exactly who took them down, but after rush hour was over a local news station was going to go out there, but the balloons were gone,” Jones says.