Receiving a mysterious that you didn’t pay for might seem like a little gift from a universe. After all, it might be something useful, and you’re typically under to return mistakenly delivered merchandise. It’s free stuff! Still, be careful: It might also be what’s known as a "brushing scam.

" And while a brushing scam usually doesn’t come with any danger to you, there are a lot of reasons you should be concerned if you receive an unexpected freebie at your door. A involves an unscrupulous vendor sending you an item you didn’t order, allowing them to create the illusion that you order it. Do that enough times with enough people, and it'll look like the item is popular.

The vendor can then also write fake reviews in your name—Amazon elevates “ ” in its reviews, giving them extra weight because it has verified that they actually ordered the item in question. A brushing scam therefore makes fake reviews look doubly legit: Someone actually ordered the item, and that verified purchaser leaves the review. Because these are shady companies, the stuff they send out is usually not high-quality.

They're often fake luxury brands or low-quality stuff, and the brushing scam helps make it look more legitimate. Okay, so the stuff might be crap, but it’s free! And you can legally keep it! So what’s the big deal if you’re passively helping scammers get over on unsuspecting customers who think you, a real, reliable person, gave it a good review? There’s typically no ha.