Stay one step ahead of the fraudsters with our series of articles giving you the lowdown on the scams they use to trick people out of their hard-earned cash - and how to avoid being taken in by them.
This week, we expose a new Facebook scam supposedly designed to spread happiness and positivity at Christmas: the "Secret Sister Gift Exchange".
How does it work?
This Christmas present scam is a play on the Secret Santa system used in many offices and groups.
It encourages people to "spread joy" by sending one so-called secret sister a gift worth at least $10 (about £8).
Participants will then be sent gifts by others who have joined the scheme, receiving up to 36 in return - according to the posts on social media site Facebook.
"I need ladies of any age to participate in a secret sister gift exchange," one said.
However, police have warned that those who take part in this gifting version of a pyramid or chain letter scheme may well receive nothing in return - and could even find the personal information they provide is used in further scams.
"Don't fall for the post popping up on your news feed about a secret sister gift exchange – it's a scam and illegal," one US police department wrote on Facebook.
The secret sister scam has so far been targeted mainly at Facebook users based in the US. But UK users of the site need to be on their guard against this and similar schemes.
The safest approach is to ignore posts of this kind completely, especially as they could lead to you getting into trouble for being involved in a fraudulent scheme.
I've been defrauded. What should I do?
Informing Facebook, for example by reporting a group using the ... tab in the top right corner, can help it to take action against people running scams on the website.
It is also important to notify any relevant organisations - such as your bank - if you think you may have shared information that could be used against you with fraudsters.
Finally, report the scam to Action Fraud (0300 123 2040).