enemy of the state? A supermarket hack, man

It has become slightly annoying visiting a wall-known supermarket and innocently setting off the theft alarms when I leave. I decided to ask the security guard what was happening and we experimented with my jacket, then phone and then wallet.

I was convinced it was the phone and had even seen other people complaining about similar effects, but in the end it turned out to be my wallet.

Apparently a single RFID card won't cause it, but put several together and their combined signal is enough to trigger 'modernised' supermarket systems. 

The security guard was quite helpful and suggested I needed an RFID-proof wallet. A truly first world problem?  I could remember enough schoolboy physics such that I could line my wallet with aluminium foil and it should block the signals like a Faraday cage.

It would work like the one that Gene Hackman used in The Conversation and then reprised in Enemy of the State, only much smaller. They are like those mesh bags they give out at some concerts to put one's phone in. 

I also discovered that there are credit card sized anti-RFID cards which can be placed dierctly in the wallet. They are also triggered by the same scanner frequencies but then send out jammer signals. Now that is worth trying, although I expect I'll be tapped on the shoulder again.