The P.S.N.I. issued the warning via social media after several such incidents were reported as having occurred in Magherafelt, Co. Londonderry recently.
"Driving along slowly in the town minding your own business then suddenly, ‘Steve... Steve... STEEEVE!!’ - some guy’s pretty much out in the road flagging you down.
"‘Sorry thought you were someone else, [you] look very like Steve though, meant to meet him here, I’m a wholesaler, was just up the town there selling stock, busy day (whips out a wad of cash) only a couple of boxes left!'," described the P.S.N.I.
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The P.S.N.I. advised anyone who experiences an incident like this to "drive off and contact us".
"And so begins the tried and tested means of sucking you into the circle of trust, except its one big circle of dodgy claims, sleight of hand, distraction techniques and high pressure sales.
"Before you know it he’s pretty much in the car doing the hard sell on the box of knives meanwhile you’re still a bit off guard from having a stranger stop you and launch into full sales mode.
"You throw out the classic ‘I’ve no money on me’ line, - gonna need to try harder than that, he didn’t flag you down opposite the cash machine by coincidence."
The P.S.N.I. added: "These occurrences in Magherafelt this week have been for boxes of knives, but instead of knives its often pillows / duvets / wooden flooring / generators / tools etc etc
"These guys have done this finely honed routine a thousand times over, only answer is to drive off, don’t get into a conversation, call us."