By Amy E. Feldman

PHILADELPHIA (CBS) - You know that moment when you hand a salesperson a big bill and she uses that marker to make sure it’s not counterfeit? What happens if it is?

In the category of Merry Christmas, sucker, a boy received a $100 bill from a relative for Christmas. Best gift ever. Turned out to be fake. Worst gift ever.

When the checker at the store he tried to use it at checked, it was found to be counterfeit. She kept the bill, then called the police. He was not arrested but the bill was confiscated. Is that legal?

If you have a bill in your possession that turns out to be counterfeit, although you won’t be charged with a crime for having it (unless you’re the one who counterfeited it), you will be out the money. If a store discovers it’s a counterfeit, it’s supposed to keep the money (give you nothing for it, since it has no value) and send it to the Secret Service.

Once you’re told it’s a counterfeit, if you get it back and then try to use it at a store with a less savvy cashier, you are violating federal law by attempting to pass a bill you know is counterfeit.

You can check for counterfeit money by holding it up to the light to see the watermark, also look for red and blue fibers running through the bill and look for a security thread running from top to bottom of the bill.

Also, next time ask your generous relative for a money order next Christmas.