I carried an old credit card that I had cut out places for my car and house key for years and had used it way to many times. I showed it to a coworker who made his own and around a year later had his wallet stolen. The thieves now not only had his credit cards and money, but his address and access to his house. He was able to change the house door locks before they used them. After that I stopped carrying it and started paying attention before I left the house.