More than 100 years ago the Australian Government made it illegal to import rum that was not already aged, in a bid to protect the local industry - much like the country's controversial ban on New Zealand apples.
But unlike the apple law, lifted last year, the rum rule remains.
It has created problems for Auckland-based rum brand Stolen, which has enjoyed wild success selling its aged white and gold rums across the ditch. Stolen launched an overproof product this month but section 105a of the Customs Act 1901 has hampered its plans to export it to the lucrative Australian market.
So the brand's founders, Jamie Duff and Roger Holmes, are recruiting "mules" to carry the product to Sydney and Melbourne, two bottles at a time.
Duff said it was not illegal, as no money changed hands and the amount was within "personal" limits. The ultra-specialty product was given, not sold, to bars to show gratitude for stocking Stolen's other products.
The "mules" were compensated with cocktails.
The overproof rum, called SX9, was available in specialty bars and not stocked in liquor stores.
"Traditionally, it's not aged so it hangs on to its characteristics," Duff said. "It's 65 per cent alcohol so you don't want it falling into the wrong hands."
Twenty-five frequent travellers had signed up so far, including Jade Hurst, 30, who travels to Sydney four or five times a year.
She responded to an ambiguous "mules wanted" poster plastered on a Ponsonby electricity pole as she liked the idea of helping a local company and thought it was quite clever.
Her first rum run, to Darlinghurst night-spot Eau De Vie, was planned for May.
Stolen had given her a T-shirt emblazoned with the word Mule to wear through the airport. "I might have a jacket over it so I don't draw too much attention," she said.