Lock Picking Is Scarily Easy
Most people feel secure in their homes behind their locked doors. And they are... But it's more because of criminal laziness than the security of locks. A friend taught me lock picking when I was in high school and it was quite a revelation to discover that in 45 minutes I could be taught how to make lock picks and then pick 95% of locks. I've had to use this knowledge to get back into my own home on a few occasions, as well as help friends get into theirs. I've never used the knowledge for evil. 
And I'm glad few other people have, either. But it's amazing when you realize that any criminal could quickly learn this skill and stroll through your front or back door in only a few more seconds than it takes you to insert and turn your key. Fortunately the same life choices and lack of ambition that make them criminals has also prevented them from learning new skills like lock picking.
Basic tutorial on lock picking:
And the frighteningly fast Bump Key method:
^Q
