During the past week, the man is alleged to have targeted at least six outlets - including in Dunedin, Frankton, Cromwell and Kaikoura - by using the same ruse to scam counter staff of cash.
In each case, the man is reported to have handed over a $100 note when buying a low-cost item such as a drink.
After talking loudly and gesturing, which police say they believe is to distract staff, he then says he has the right change in coins and asks for the note back, but not before pocketing
$40 to $60.
The man is described as a middle-aged Asian, wearing a suit, Dunedin youth and community services Senior Sergeant Mark Crawford says.
''This seems to be a fairly specific modus operandi, involving a $100 bill.''
The man was believed to have been active in the Dunedin area late last week, targeting two food outlets and a non-food outlet.
He used the same routine at Subway outlets in Frankton and Cromwell on Sunday and Kaikoura on Monday, although that attempt was not successful, police said.
Snr Sgt Crawford warned counter staff to be vigilant when carrying out transactions, and asked anyone who may have fallen victim to the scam to contact police.
