Do you have a friend on Facebook who's invited you to be part of a Secret Sister Gift Exchange? You'd think this would be a great idea, but before you sign up, you need to know a few things.

I hate being the bearer of bad news during the holidays but this is something you should probably be aware of as the holiday season gets into full swing. We saw this scam pop up on social media last year and it is once again making the rounds on Facebook.

Basically a 'new and improved' version of the old and fabled 'chain letter', the Secret Sister Gift Exchange asks you to buy a gift card of $10 or more and mail it to someone on the list. You then add your name to the master list, which in turn allows you to receive up 36 gifts.

Now first and foremost, if it sounds too good to be true, it probably is. Most people don't see anything in return and even worse, no one knows who really has access to this list with your name and address on it - even if one of your friends started the thread - it's often part of something bigger.

Secondly, this is an illegal act and you're not helping anyone you know on Facebook. The United States Post Office considers this to be a chain letter, which has been determined to be a form of gambling - hence, illegal.

[Chain letters are] illegal if they request money or other items of value and promise a substantial return to the participants. Chain letters are a form of gambling, and sending them through the mail … violates Title 18, United States Code, Section 1302, the Postal Lottery Statute.

Your best bet is to do it with people you actually know: Secret Santa, White Elephant Exchange or heck, even Elfster.