When you give your car keys to a mechanic or valet, make sure your only give them the keys to your car, do not give them your entire key ring with your house key on it. Think about it. Sitting in the glove box of your car is your registration. And it has your address on it. And you've just given your house keys to someone to hold for several hours.

Now 99.9999% of the time, nothing will come to this. But there are unscrupulous people out there, and some of them will take advantage of this. By making a copy of your house key they then have an easy way into your house, and they know where your house is.