Another social engineering hacking method is to leave USB hard drives for unsuspecting people.
NetworkWorld.com article goes into some details of why the USB hard drive is insecure and can be easily programmed with malware (malicious software).
This malware can be designed to inject itself into your computer, or a server. and without you knowing it can infect your systems.
there are many ways for your computer to get infected, dont make it easier for the bad guys.
Only connect USB drives to computers that can format and wipe the USB drive and then you can use it.
We typically format the drive with a Linux system, and to be safe use a LiveCD system, so that the Linux system does not get infected either.
You never know what a USB stick looks like – including novelty Storm trooper USB hard drive 🙂