SIOUX CITY, Iowa (KCAU) – Authorities are warning folks not to believe everything they see on Facebook.

You may have seen a $75 coupon for Costco on social media, except that it isn’t real.

These types of scams are pretty common.

It’s actually the second year in a row the company has had to debunk a coupon scam.

The fake offer prompts users to click on a link to get the coupon.

The scammers may be trying to get your email address to sell to spam companies, or simply get revenue from click advertising.

More malicious fake coupons will install malware after tricking you into downloading a coupon installer.

Sometimes those fake coupons are convincing, especially if you see it shared by people you know and trust on Facebook.

According to the Identity Theft Resource Center, here are some ways to spot a coupon scam:

One way is to Google the offer, such as “Costco $75 coupon” plus the word scam to see if it’s been investigated.

Another way is to go to the store’s website to see if they have any mention of a coupon. You can also just call the store directly.

The Better Business Bureau warns consumers that they’ll see an increase in scams during the holiday season, especially on social media.

One such scam is the “secret sister gift exchange” The scam was viral in 2015, but it’s circulating on Facebook once more.

Posts tell participants they will get up to 36 gifts in exchange for sending one $10 gift.

Users are encouraged to invite others to participate as well.

However, “secret sister” and other gift chains are pyramid schemes and are classified as illegal gambling by the U.S. Postal Inspection Services.

The best protection is to simply ignore anything that seems too good be to be true, especially on social media.