For several months I've been setting of store security systems maybe half the time when passing through. The kids found this rather funny and started taking bets if the alarm would go off. (There was much cheering either way, which I'm sure looked pretty odd.) Recently, I took the plastic card holder out of my wallet for some reason and found one of those RFID tags wedged way in the back of its slot. So, if you buy someone a wallet for Christmas, be sure to tell them to take out the tag. Or, depending on your demeanor, make sure it's really stuffed in there...