DR Congo banks on cleaning up its mucky money
They are stuffed under mattresses, in bras and even down underpants.
So it is hardly surprising that the Democratic Republic of Congo's banknotes are dirty.
To try and clean up its mucky money, the government is urging the Congolese to look after their francs in a national advertising campaign.
Sung by two of the country's most popular singers, it has become quite popular in the capital, Kinshasa.
"Congolese bank notes stay in circulation for years," says local journalist Michael Kavanagh.
"They never end up in banks, they just end up torn, screwed up and extremely dirty," he tells the BBC World Service's World Business News.
But it is not just to clean up its dirty cash. The authorities think that if people can learn to love their francs, they will also have more respect for the national economy.
Replacing the dollar
The Congolese franc is relatively young, so many people prefer the older, more established US dollar.
On pay day, they rush to change their francs into dollars.
"People have a memory of a time when inflation was 10,000% and there is a fear that such a thing could happen again," Mr Kavanagh explains.
"You find that any big transaction in [DR] Congo takes place in US dollars and about 90% of bank holdings are in US dollars - not that there are many holdings in the Congo," he adds.
Senator Saturnin-Blaise Luon believes that the circulation of dollars penalises the Congolese economy.
"When you buy and sell in dollars, you're working for the American economy, not your own," he says, expressing the president's view that a strong currency is both a reward and a building block of a nation's economic health.
The government is hoping for a strong economy built on a strong currency. For years, there has been very little faith in the Congolese franc.
The Central Bank has slowly been restoring faith in the currency with simple macro-economic policies.
In December, it was reported that inflation averaged about 8.8% over the previous 12 months, down from almost 50% in 2009.
Samir Jahjah, head of the International Monetary Fund (IMF) in DR Congo, welcomes any improvement.
"The volatility of inflation hits [DR] Congo's poor where it hurts most, hiking the price of basic necessities by 40% since 2009 and forcing people to buy chicken cut up into single chunks instead of being able to afford a whole one," he says.
"High inflation is a tax on the poorest," he adds. "They cannot hedge against inflation by holding dollars."
Apart from deepening the rich-poor divide, the two-currency limbo also places a financial strain on Congolese commercial lenders - and that is hampering their ability to provide normal banking services.
The central bank obliges them to place 7% of the value of their deposits in local currency, even if customers first place their money in dollars. That obliges them to rent or buy francs from banks or the central bank at high rates.
Keeping inflation low and stable is crucial to President Joseph Kabila's vision of getting more people to actually start investing in the Congolese franc - putting it into banks and ending the use of the US dollar.
Only then would the government be able to have more control over its monetary policy. It would even be able to denominate debt in the Congolese franc.
In the meantime, among the more bizarre souvenirs sold by street hawkers are the brightly-coloured banknotes that circulated when President Mobutu Sese Seko ruled what was then Zaire.
The leopard-emblazoned notes had a face value of up to five million zaires. But by 1994, they were next to worthless as prices soared by an annual 10,000%.
Only the introduction of the US dollar as legal tender that same year managed to tame the galloping inflation, with the legacy that 90% of bank deposits are to this day held in that currency.
Some people argue that DR Congo would fare better if it got rid of its own currency altogether, as Zimbabwe did in 2009 after suffering years of hyperinflation.
But such a step would not fit with the president's determination to show his country can stand on its own feet.
DR Congo's six neighbours to the north use their own single currency, the French Treasury-backed central African franc, but the ex-Belgian colony does not share such French ties and is also keen to nurture relations in southern Africa.
Many investors support his idea, seeing a strong franc as a prerequisite for the long-term goal of creating a more mature economy.
If DR Congo can benefit from its vast mineral reserves and the prospect of oil, it could ultimately fulfil its potential as a consumer market of 67 million people.
The government is trying to change the population's perception of their currency, but it still might take some time.