(Meredith) -- The "Secret Sister" gift exchange is making the rounds again on Facebook, just in time for the holidays.
It starts off as a seemingly harmless Facebook post that calls for a gift exchange between friends, but it's actually an illegal scam. The exchange claims that people will receive up to 36 gifts if they send one gift valued at $10.
Participants are then encouraged to invite others to join in the holiday gift exchange, where they will receive information on where to mail gifts.
Here's the type of post you want to avoid:
Multiple law enforcement agencies have issued warnings about the "Secret Sister" gift exchange as recently as this week. On Monday, the Wauwatosa Police Department in Wisconsin posted an alert to its Facebook page about the scam, citing the Better Business Bureau.
"This is a typical pyramid scheme." the BBB said in its warning. "This is on Facebook instead of the old way of using letters because social media allows it to spread a lot faster. Pyramid schemes are illegal either by mail or on social media if money or other items of value are requested with assurance of a sizable return for those who participate."
The exchange has been around for several years. Back in 2015, the U.S. Postal Inspection Service also posted a message to its Facebook page, cautioning people to avoid it
"The people at the top of the 'pyramid' benefit most--and might actually receive the items promised," the post reads. "However, for everyone to receive what they’ve been promised, each layer of the pyramid must attract new recruits. It’s mathematically impossible to sustain."
Know the warning signs
If you receive a chain letter by mail, email or social media, especially one that involves money or gifts, the BBB recommends:
Start With Trust®. Check with the BBB before becoming involved in suspicious and possibly illegal activity.
To avoid this scam, the best thing to do is completely ignore it altogether. Do not give out personal information to anyone.
Chain letters via social media and U.S. mail that involve money or valuable items and promise big returns are illegal. If you start a chain letter or send one, you are breaking the law.
Chances are you will receive little or no money back on your “investment.” Despite the claims, a chain letter will never make you rich.
Some chain letters try to win your confidence by claiming they’re legal and endorsed by the government.
For more information on the "Secret Sister" gift exchange and similar invitations, click here.