How do I avoid an ‘unexpected item in the bagging area’?

Nothing is more likely to tip me into a full Michael Douglas meltdown than an ‘unexpected item in the bagging area’. The 30-second dangle, while you wait for the poor assistant to come and check that you’re not making off with a 42in flatscreen instead of a tube of Pringles, is dangerous for my blood pressure.

After years of infuriating trial and error, I’ve mastered a few techniques for avoiding the ‘unexpected item’ and other robo-till errors, which I’ll share with you now.

Don’t put your bags in the bagging area immediately

You’re a good human being. You’ve bought your own shopping bags to stop the Earth turning into a giant ball of Tesco, and being the logical type, the first thing you do when arriving at the self-checkout is place your bags in the ‘bagging area’. Crazy mistake. First press the button on the machine that says ‘Weigh your own bags’ or something similar, and then place the bags in said slot. Do it beforehand and the till is likely to throw an Elton John-like hissy fit.

Make sure the bags are fully on the scales

The bagging area obviously has scales underneath it that check you’re not sneaking a bottle of Teacher’s in with your bananas. But the bagging area is a metal minefield, with panels – such as the one directly underneath the carrier bags on Tesco’s tills – that prevent the bags from being weighed properly. Thus, when you pop your Sunday joint in the bag, the till is only registering a bag of Quavers and calls over the assistant.

Scan a heavy item first

If you’ve got a four-pint bottle of milk, a water melon or something else substantial in your basket, scan that first. This seems to help calibrate the scales and make the till more likely to trust you when you place in a near-weightless pack of Parma ham further down the line.

Jiggle the bag around

Once the robo-till has called for backup, you often face a two-minute wait while the harassed teenager in charge deals with the eight other customers who’ve got similar problems. You don’t have to wait for Nathan to reach you to get past the till’s plea for help, however. Often jiggling the bags, so that the scales fully recognise the expected weight of the shopping, is enough to make the problem go away.

Scan your booze early on

There are certain items that the supermarkets don’t or can’t legally trust the robo-tills to deal with: knives, alcohol, perfume, Extra Strong Mints. Make sure you scan anything that might require Nathan to come over and press the most depressing button in the world – ‘customer is CLEARLY over 25’ – early on. Most robo-tills let you finish scanning the rest of your items while you’re waiting for Nathan to stop chatting up the Saturday girl on fruit ‘n veg.

Get the kids to back off

Nothing is more likely to send the robo-till into a fit of shoplifting paranoia than the kids sitting on the scales. If you’ve got the patience of a nun, you can get the kids to do the scanning bit. If not, do what every other parent does: send them to play with the demo iPhone while you get on with the packing.