Burger King are letting you trade your passport for free burgers – but there's a catch

Burger King are letting Swedish citizens use their passports to claim free burgers, but there's a pretty major catch; you might just ruin or void your passport in the process.

The fast food chain is now offering a new deal in Sweden as part of its "World Gourmet" series.

Now, Swedish citizens can get a Burger King stamp on their passport, which they can then use to redeem a free burger in Sweden.

That's right; stamp your actual, legal passport and you get a free burger.

Anyone with a Swedish passport can redeem the offer up to five times, cashing in stamps for unique burgers inspired by international travel hubs like Argentina and France.

So why is the offer just for Swedes? According to the 2019 edition of the Henley Passport Index, the Swedish passport was one of the strongest in the world, granting visa-on-arrival access to 187 countries.

Not that it matters right now, with borders still closed across the globe and travel heavily restricted due to the coronavirus pandemic.

According to Burger King Sweden, it's locals' inability to travel that inspired the deal.

"As the Swedish State Department still recommends citizens not to travel, we'll let people repurpose their passport to experience tasty foreign flavors for free here in Sweden," Daniel Schröder, marketing director at Burger King Sweden, said in a press release.

But burger lovers who are eager to cash in on the deal need to know that they stamp their passports at their own risk, as it may very well make their passport invalid.

According to the Australian Department of Foreign Affairs and Trade, unauthorised souvenir or tourists' stamps can make passports "invalid for travel".

And while it's unlikely many of us will be travelling internationally any time soon, a passport is still considered a legal document.

9Honey have reached out to Burger King Sweden for comment.