Canada's new plastic money may give you a little more bang for your buck.

New documents show a focus group mistook a strand of DNA on the $100 bill for a sex toy.

Most people also thought the see-through window on the new polymer notes was shaped like the contours of a woman's body.

Others looked into the port holes of a famed Canadian icebreaker and saw a skull and crossbones staring back at them.

These are just some of the offbeat images focus groups thought they saw on the plastic bank notes that go into circulation next month.

Internal documents show the Bank of Canada fretted that Canadians would find all kinds of unintended images on the new bills. So the bank used focus groups to spot "potential controversies."

Security features stir imagination

"The overall purpose of the research was to disaster check the $50 and $100 notes among the general public and cash handlers," says a January report to the central bank.

The Canadian Press obtained the report along with other documents under the Access to Information Act.

Almost every group thought the see-through window looked like a woman's body, but participants were often shy about pointing it out.

"However, once noted, it often led to acknowledgment and laughter among many of the participants in a group."

The new $100 bills feature two portraits of Prime Minister Robert Borden.

On the other side of the bill, there's an image of a researcher at a microscope and a depiction of the double-helix structure of DNA.

But the DNA strand evoked something else. A Vancouver focus group thought it was "a sex toy (i.e., sex beads)."

Others thought it was the Big Dipper.

There was no mistaking the microscope, but when focus groups flipped over the bill they noticed the edge of the instrument showed through like a weird birthmark on Borden's cheek.

Respondents also thought the former prime minister was either cross-eyed or that each eye was looking off in a different direction, the report says.

"Others felt that the PM's moustache is unkempt."

Clockface or religious symbol?

Every focus group thought they saw religious iconography on the face of the Peace Tower clock.

"It was often described as 'The Star of David.' Others referred to it as a 'pagan' or 'religious' symbol," the document says.

"This evoked a response that suggested that the depiction of religious icons on Canadian bank notes was strongly resisted."

The research also raised red flags about the new $50 bill.

Some focus groups saw spooky shapes inside the port holes of the research icebreaker CCGS Amundsen.

"The small white windows at the front of the icebreaker's bow were believed to have faces in them," a report says.

"One respondent who saw faces in the windows suggested that they looked like skulls and crossbones."

Some assumed the Amundsen was a foreign ship while others saw the Stars and Stripes fluttering from the anchor port. The Montreal group noted that oil companies have used the coast guard ship.

The shape of Newfoundland and Labrador was often mistaken for other forms, including a bird, Pinocchio and a war plane.

Others thought Inuktitut writing on the bill, which translates to the word "Arctic," was some kind of secret code or a set of mysterious symbols.

Bank of Canada spokeswoman Julie Girard said the bills got tweaked after the focus groups.

"Before and after those focus groups, there were design changes for multiple reasons," she said.

The first bills to go plastic will be the $100 notes in November. The $50 notes will follow next March. The rest of the plastic money will be in circulation by the end of 2013.

The polymer bank notes have security features that make them harder to fake than paper money. But focus groups called the bills "Monopoly money" and said they did not feel as real as paper money.