Police are warning people about a "secret sister gift exchange" that is making the rounds on social media, including Facebook.
The secret sister gift exchange promises that if you buy one $10 gift for someone and add your name to a list, you'll get between six and 36 gifts in the mail.
Authorities say not only is the promise too good to be true, but it is also illegal.
Caitlin Coller of Danville, Pennsylvania, was among those tagged in a Facebook post promoting the gift exchange.
"At first when I read it, I thought it was pretty cool," said Coller. "The girl who tagged me in it is pretty reliable and is really nice, so it seemed like something she came up with. It seemed like this original thing."
But it's not an original thing. According to investigators, the secret sister gift exchange is a scam.
"You have no idea who you're giving that information to, so ultimately what you're setting yourself up for is identity theft," said Danville Police Chief Eric Gill.
The post asks you to mail a gift to someone on a list add your name and address to the list and you'll get gifts in return.
Gill says it's illegal. The United States Post Office considers this a chain letter which is a form of gambling.
"Sending your private information to somewhere where you have no idea where it's going to go is very foolish," the chief said.
Police in Tennessee also posted a warning to their Facebook page this year:
The secret sister gift exchange was popular in 2015 and is making the rounds again.
Rebecca Kurtz of Lewisburg saw it on Facebook but thought it was questionable.
"My cousin has it on hers and I thought, OK, I'm not going to do it, though, because I don't know half the people," she said.
If you want to do a gift exchange, the chief suggests doing one through work or with friends you personally know.
"It would be easier to go down to the local store and purchase something for $10 and wrap it and give it to them."
If you are invited to take part in the secret sister gift exchange, you can report it to Facebook.
U.S. Postal Inspection Service has this guidance:
“There’s at least one problem with chain letters. They’re 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 (or delivering them in person or by computer, but mailing money to participate) violates Title 18, United States Code, Section 1302, the Postal Lottery Statute. (Chain letters that ask for items of minor value, like picture postcards or recipes, may be mailed, since such items are not things of value within the meaning of the law.”