Want to safely hide a spare house key? Here are a few tips. Burglars, don't read this story. It's a horrible feeling: You arrive home and discover that you lost your key. If only you had a spare you could use to gain entry. Actually, there are numerous ways to hide that spare key. Let's get the obvious ones - and by obvious we mean dumb - out of the way. Don't leave a spare key under the doormat. Even the most dim-witted ...