Folks at DDB South Africa were brainstorming for a clever way to promote Hubba Bubba Bubble Tape, a chewing gum made by Wrigley’s that comes in a six-foot-long rolled strip, when an idea appeared on the wall, literally.

Someone looked up and noticed a poster that was held in place at the corners by soft putty, recalls copywriter Stuart Turner. “When we saw the big bumps in each of the four corners, the idea just came to life.”

What came out of it was a giant, billboard-size poster that looks to be held in place with giant wads of chewed gum. There's an image of the gum with the words "6 feet of gum" printed on vinyl help up at the corners.

The idea: Hubba Bubba Bubble Tape is gummy enough to hold up a huge sign.

“Unfortunately, we could not chew enough gum to make the billboard stick up for real,” jokes Turner.

To create the illusion, the agency created plastic molds of what looked like clumps of chewed gum and hung them from wires so it would appear the clumps were indeed holding the poster in place.

The ad went up recently for a month-long run in Johannesburg.

It would be nice to say the idea was thought so clever that other such posters are set to go up. It's not to be. The billboard turned out to be such a challenge that it was decided it would be the first and the last.