Rich Pedroncelli, Associated Press
In this photo taken Dec. 7, 2010, Sawyer Rummelhart, 4, points to the "The Smurf's Village" app on his mothers iPad, at his families home in Gridley, Calif.

If you hand your phone to that child begging to play a free game on it, beware the hidden charges.

Many parents are being hit with huge bills because their son or daughter started playing a game that cost nothing to download onto their cell or smartphone only to find their children bought something inside the game to help them progress or win. It's a little like getting Monopoly as a gift but then needing to buy a "Get Out of Jail Free" card to enhance your chances to win.

One 8-year-old racked up $700 playing an iPhone app game called Bakery Store. The irony is that the boy's mom is tech blogger Lucy Gray, who admitted she was embarrassed. The iPhone store refunded her charges.

An 8-year-old girl managed to do twice as much damage as Gray's son, the Washington Post reported Tuesday. All little Madison was doing was dressing up her mushroom home in The Smurfs' Village.

The stories are many, and so are the angry parents. One boy, wanting to speed up the same game, in which the cute little blue Smurfs build villages and farms, bought a bushel and 11 buckets of Smurfberries. He didn't know he was charging $66.88 to his mom's credit card, according to an AP story. The story said six of the 10 apps that gross the most money are free downloads with what are called "in-app purchases." Two games, Bakery Store and Tap Zoo, have "in-app purchases that cost $100 each and can be bought in two taps of the phone.

After that story ran, Capcom Entertainment added a warning that pops up on Smurfs' Village, AP reported, but it also bumped the cost of wheelbarrow for Smurfberries from nearly $60 to $100. The game also requires a password, but it doesn't take effect for 15 minutes. No warnings pop up on Bakery Store or Tap Zoo.

There's plenty of money to be made. The Apple App Store passed 10 billion downloads on Jan. 22.

And Smurfs are popular. A Los Angeles Times blog described them this way: Smurfs, those cute little blue cartoon dwarfs inspired by the trolls in Nordic fairy tales and beloved by kids (and childish adults, you know who you are) since the 1950s, are arguably one of the greatest gifts Belgium ever bestowed on the world.

But the charges for in-game upgrades drove one father to launch a Facebook group to protest, according to Associated Media.

Many of these parents could have avoided the problem if they had read the review of The Smurfs' Village by Common Sense Media when the game came out. The review was posted in November and rated the game "Iffy" for ages 8-12. "... This game encourages players to spend real money on virtual 'Smurfberries,' the reviewer wrote. "Containers of the berries, which cost from $5 up to $100, allow players to speed up the action (rather than wait, say, two hours for a house to be built) or to earn special in-game items that can only be traded for Smurfberries."

Common Sense Media called the game one of the so-called "velvet-rope" apps that can be obtained for free but make in-game sales enticing.

"In order to get the most out of Smurfs' Village, players need to spend real money to buy extras," reviewer Christopher Healy wrote.

After the Post story appeared Tuesday, a Massachusetts Congressman called on the Federal Trade Commission to review the marketing practices of apps made for the iPhone and iPad.

"Companies shouldn't be able to use smurfs and snowflakes and zoos as online ATMs, pulling money from the pockets of unsuspecting parents," Rep. Edward J. Markey, D-Mass., said in a statement posted on his website.