Games on Facebook have become popular with teenagers. And it may cost the social networking giant some real money.

A parent is suing Facebook, claiming that by allowing minors to purchase credits for in-game use, the company is sidestepping consumer protection rules, Gamasutra reports.

In a complaint filed in the U.S. District Court for the Northern District of California, Glynnis Bohannon alleges that Facebook’s requirement that children under the age of 18 obtain a parent’s permission before they buy the credits is insufficient to prevent the transactions.

Bohannon is demanding a refund for her own child’s purchases of Facebook credits, as well as refunds to all parents and guardians of children in the U.S. who have made similar purchases. The suit could cost Facebook $5 million — the amount of such sales — if the court rules in favor of Bohannon.

The Facebook suit is similar in nature to lawsuits filed against Apple (NASDAQ:AAPL). In those suits, parents allege that games for iPhones, iPods and iPads, purchased through the company’s App Store, allowed their children to buy virtual items for use in the games without their consent.

ABC News notes that some children managed to rack up significant bills through such purchases.

The parents called the situation a case of “bait and switch,” arguing that the games were advertised as being free, yet required in-game purchases for players to advance to higher levels.

One game called Smurf Village allowed players to purchase 1,000 in-app credits that cost $59 in real cash.

Responding to complaints last year, Apple changed the app store’s policy to make it harder for kids to make purchases without their parents’ permission. The litigants claim the new policy isn’t enough.