The Better Business Bureau is warning consumers not to get sucked in by the 'Secret Sister' gift exchange circulating on social media. It's a scam - and it's illegal.

You may have seen the post on Facebook, inviting you to participate in a 'Secret Sister' gift exchange. "Who doesn't like presents," you might think. Well, don't click that link: it's a scam.

The invitation seems innocent enough - just buy a gift for one person, and you'll be showered with gifts in exchange:

"You have to buy one gift valued of at least $10 and send it to your secret sis (Hello, Amazon!) You could then receive unlimited gifts in return depending on who participates.

This is so much fun! I love sending a gift to a complete stranger knowing that she would have a bright spot in her day because of what I sent. 

Let me know if you are interested, and I will send you information about your sister. 💃🏼 We all could use some happy 😃 mail 📬!!

SO...Who’s in? Anyone is welcome to join the fun just comment “I’m in!"

Credit: Facebook

According to the BBB, it's actually a pyramid scam and therefore, illegal. On top of that, says the BBB, "just like any other pyramid scheme, it relies on the recruitment of individuals to keep the scam afloat. Once people stop participating in the gift exchange, the gift supply stops as well, and leaves hundreds of disappointed people without their promised gifts."

"It should be noted that pyramid schemes are illegal in the US and Canada. The U.S. Postal Inspection Services explains that these gift exchanges are considered a form of gambling and that participants could be subject to penalties such as jail time, fines or a lawsuit for mail fraud," adds the BBB.

Plus, sharing your email address or other information could make you vulnerable to identity theft.

So, go ahead and organize a Secret Santa gift exchange with your friends or co-workers, but don't get duped by the 'Secret Sister.'