A Shawn Mendes marketing campaign encouraging young fans to buy every single copy of the teen-pop heart-throb's new album from local stores is eliciting outrage from child advocacy groups.

The 16-year-old Toronto native trumpeted the release of Handwritten with a "#HandwrittenBuyouts" Twitter contest, urging his swooning fans to purchase every last Mendes CD from store shelves.

On Tuesday afternoon, he tweeted to his nearly three million followers: "Go to stores today & buy all the album copies ! U can find a .GoldenShawnAccessPass & meet me ! .HandwrittenBuyouts."

Attached to the tweet was a polished image repeating the instructions and touting a grand prize for two to meet Mendes and watch him perform in a warm-weather destination. Other prizes include meet-and-greet access and merchandise.

And judging by replies to the tweet — which was retweeted about 7,000 times and got more than 12,000 favourites — fans of the Vine sensation were eagerly heeding his command.

One devotee tweeted a photo of herself clutching a colourful wad of Canadian bills with the message: "I guess all my babysitting payed (sic) off! :)"

Another female fan from Ontario tweeted a photo of 16 copies of the album strewn across her bed — along with a picture of the total bill: $255.38.

An 'unethical' strategy 

Multiple child advocacy organizations raised questions about the strategy on Wednesday.

"I think that's really concerning, considering his appeal to younger fans," said Campaign for a Commercial-Free Childhood associate director Josh Golin, who called the campaign "unethical."

"Younger fans are unlikely to understand the odds of contests — and that their chances of winning any type of contest are astronomically against them. And then to encourage kids to buy multiple copies when there's no use for multiple copies is particularly exploitive."

You're taking advantage of people who don't necessarily have the critical-thinking skills yet to be able to make good decisions about managing their money. - Matthew Johnson, director of education for Ottawa-based Media Smarts.

Following Mendes's tweet, pictures began rolling in from fans dutifully bingeing on the earnest Life of the Party guitarist's full-length debut.

Mendes himself retweeted photos of fans showcasing their Handwritten hauls in multiple ways: fanned out in their fingers like a poker hand; spread about the front seat of the car; or stacked, neatly, 20 discs high.

"The harm could be that kids are going to be spending money that they don't really have — money they might need for other things — (and) that you're taking advantage of people who don't necessarily have the critical-thinking skills yet to be able to make good decisions about managing their money," said Matthew Johnson, director of education for Ottawa-based Media Smarts.

"When you know your audience is fairly young, obviously you do want to reach them, but you could definitely make an argument that it's irresponsible to be encouraging young people to buy multiple copies (of an album)."

Most of the fans pictured tended to be adolescent or pre-teen girls.

Lack of parental oversight

Although some seemed to be alongside their parents, Johnson points out that social media allows advertisers to reach children without as much parental oversight as other platforms.

Shawn Mendes

Shawn Mendes poses for a selfie with a fan at Arthur Ashe Kids' Day prior to the start of the 2014 U.S. Open on August 23, 2014 in New York City. (Chris Trotman/Getty Images for USTA)

"When your kids are watching a commercial on TV, there's a reasonable chance you might be sitting next to them or walk into the room," Johnson said.

"(You can then) help your kids understand how a commercial might be misleading, or understand how it might be playing on their emotions.

"But because these messages are being delivered in a context where it's probably only the child who's going to see it ... parents don't really have that opportunity."

Added Golin: "I imagine most parents would be shocked to know their kids are being urged to clean out a store of an album."

Universal Music Canada didn't immediately reply to a request for comment.​