What do you get when you blend scarcity with a drink that has 3x the daily recommended sugar intake? For Starbucks, the answer was: a winning social media strategy and the best mobile campaign of the year.

In April, the coffee chain with 8,000 stores in the U.S. unveiled a limited-edition drink that appears to have been designed not so much for its flavor, but to spark buzz online. The "Unicorn Frappuccino" was a neon-colored fruity concoction that transitioned from sweet to sour and got some less than glowing reviews. Despite having a divisive flavor, the photogenic beverage turned customers into a social media army that fueled nearly 155,000 posts on Instagram and drove major foot traffic with those clamoring to taste the magic before it sold out.

Leveraging Instagram and FOMO

The social media buzz the $5 drink prompted was exactly what Starbucks intended. With the release of the Unicorn on April 19, the brand smartly capitalized on the trend of sharing food photos online and consumers' growing sense of FOMO (fear of missing out).

"It's sort of peer-to-peer, isn't it?" social media strategist Keith Keller said about many consumers' desire to be involved in the zeitgeist. "[Starbucks] took something that was fun and turned it into a business success."

It was a little flare in the dark, a little bright spot for one week in the history of Starbucks.

— Keith Keller, social media strategist

The Unicorn appears to be part of a larger digital brand strategy at Starbucks that also includes integrating artificial intelligence technology into its iOS app and launching a reorder skill for Alexa-powered devices. Much of this comes as part of a five-year plan first outlined last December to boost growth and set the tempo for what Starbucks' new CEO Kevin Johnson plans to bring to the mobile table.

The company said same-store sales jumped after the Unicorn's launch and continued in the following weeks.

Drinks as creative canvases

Starbucks has become known for converting its drinks into canvases for creative marketing campaigns, as the Unicorn — and the brand's now 20 years of holiday cup designs — demonstrates.

As rare as... a unicorn. The color-changing, flavor-changing #UnicornFrappuccino—here for a limited time at participating stores. pic.twitter.com/TaIQrF8fac

— Starbucks Coffee (@Starbucks) April 19, 2017

After the Unicorn rose to stunt-food stardom, Starbucks tried to mimic the success weeks later with the Midnight Mint Mocha and Zombie Frappuccino. The drinks were met with less fanfare but underscore the brand's growing focus on social media as mobile becomes a larger driver of its business.

Starbucks isn't alone in eyeing stunt foods and social channels to boost consumer engagement online. In April, Taco Bell similarly leveraged Instagram and micro-influencers to promote off-kilter items like the Naked Chicken Chalupa to appeal to younger customers that are generally more involved on mobile platforms.

"It was a little flare in the dark, a little bright spot for one week in the history of Starbucks," Keller said.

The viral craze of the Unicorn Frappucino might mark a pivotal moment in the evolution of Starbucks' mobile marketing strategy. However, recent analysis suggests the brand's social clout has diminished in the months since the stunt, which means it will need to continue to innovate in 2018 if it wants to regain ground in a competitive QSR category and retain positive consumer word of mouth.