LOS ANGELES -- (KTLA) -- 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.