Lower than low: stealing from the Girl Scouts

Someone is cheating Girl Scouts, using fake $20 bills to buy cookies.

One troop in Bremerton, Washington is out $100, and some fear the fraud is spreading to other Girl Scout troops.

Beneath the cheer of the annual Girl Scout cookie sale in Bremerton smolders a flash of anger and betrayal.

Seven-year-old Silvia Swanson helps collect the money that funds their programs.

"We get to go camping, the zoo, swimming pools," she said.

But the girls found out someone used fake $20 to buy cookies.

"That makes you feel really mad," said Swanson.

"It's just beyond me," said Deborah Bernard, customer. "I can't even imagine that. These are little girls."

Trooper leader KC Gettings made the discovery Saturday while making change.

"I went to the bank, right inside Safeway, and she told me two of the $20s were fake," said Gettings.

Gettings quickly left, returning with a counterfeit detecting pen.

Its mark shows yellow on real U.S. currency, but the mark turns black on fake money.

She discovered an additional $60 in fake bills.

That brought the total to $100 Troop 40411 may make up themselves.

Two of the bills even had the same serial number.

Troop 40411 isn't alone; others around Bremerton invested in the pen.

"Another troop has come to buy them because they noticed they were getting fake money," said Gettings.

She said they're being told to stop accepting $20 bills unless they use the pen.

But who is passing the fake money is still a mystery.

Silvia Swanson knows what she'd do if they try again.

"I'd call the cops, that's what I'd do - call the cops," said Swanson.

Troop leader Gettings tried to report the crime, but the local police station is closed on weekends.

She planned to file a report on Monday.

In true Girl Scout fashion, the troop is learning from the ordeal.

Each member will earn a "fraud badge" because they helped uncover the crime.

They'll be back out, with counterfeit detecting pen in hand, next weekend.