Sugar has an image problem.

As awareness has grown around healthy eating – with particular focus in recent years on the peril of sugar – sweet treats have been losing their lustre, especially those designed to appeal to children.

Consider Dunkaroos, the snack with the cartoon kangaroo mascot. The cookies packaged with a glob of icing to dunk them in were a huge hit when they launched in Canada in 1992; General Mills Canada couldn't provide enough to keep up with retailers' orders. At the height of their popularity, Dunkaroos commanded roughly 8 per cent of the entire granola bar and fruit snack category in Canada, according to the company.

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Times have changed. It's now been about 10 years since General Mills halted its marketing support for the brand. In the United States, it was discontinued entirely in 2012. Here, it's racked up about $5-million in sales in the last 52 weeks, a relatively tiny portion of a $600-million category.

Now, General Mills is trying to revive the product with a new campaign, on a shoestring budget. The company has signed on to the "Canadian Children's Food and Beverage Advertising Initiative," agreeing to only advertise products to kids that meet certain nutrition guidelines. But this time, the Dunkaroos campaign won't be aimed at kids: It is targeting adults.

On Tuesday, the company will unveil "Smugglaroos," a website that encourages Canadians who are travelling to the United States to sign up to bring the snack across the border to Americans who cannot buy them in stores.

The company has a list of safety tips on the website, including only meeting in public places and bringing along a friend if possible.

"Online, we started to see that there was cross-border shopping: people were posting that Americans could purchase Dunkaroos online for grossly inflated prices," said General Mills marketing director Jason Doolan. "It was a wake-up call. … There is still affinity for this product."

It's not the first time General Mills' advertising has been built on adults' nostalgia for the treats they grew up with: The company stopped selling Count Chocula in Canada in 2005, but in 2014 brought it back as a limited-time Halloween promotion. It did so well that last Easter, General Mills did the same with Trix.

According to the company, nostalgia is a particularly strong purchasing factor for millennials, who grew up in the '80s and '90s and are now adults.

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It has employed a similar strategy with Lucky Charms cereal since 2012: A current ad running online features 20-somethings eating the cereal as a nighttime snack around the campfire, and a recent ad that ran on television showing an adult in camouflage stealing the cereal from a friend.

Since Lucky Charms began advertising to millennials, sales have grown, including an 8-per-cent jump in the past 52 weeks.

"It's a sweet spot for us," Mr. Doolan said. "We've seen great success with some of these other products, going after solely an adult audience."

Mr. Doolan does not expect "Smugglaroos" to really take off as a service for cross-border sugar mules. Even if only a few people actually act as small-scale importers for cookie-craving Americans, the idea is to create buzz and conversation on a budget. That includes using the slogan "Make America Dunk Again" – a riff on Donald Trump's campaign slogan – which the company has printed on hats.

"[General Mills'] U.S. marketers are watching it very closely," Mr. Doolan said.

The campaign represents a last-ditch effort to revive an ailing brand, which Mr. Doolan said could be discontinued if sales don't improve. (Think of the campaign as a cookie-protection racket.)

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"It is a real and present danger," he said.