The USB Killer is infamous (but ingenious). Plug it in, and within seconds your computer is dead, motherboard fried thanks to a high voltage dose of electricity, along with any other nearby components. This video shows you how it works, but the takeaway is clear: Never connect random USB devices to your computer.
It's Evil Week at Lifehacker, which means we're looking into less-than-seemly methods for getting shit done. We like to think we're shedding light on these tactics as a way to help you do the opposite, but if you are, in fact, evil, you might find this week unironically helpful. That's up to you.
Of course, the folks behind the USB Killer also have a USB Shield that will protect a device from it, and not all devices are susceptible to the USB Killer (for example, this video shows how ineffective it can be against smartphones) but the sheer possibility of having someone plug one of these into your computer and instantly kill it should be enough to remind you of one basic truth of information security:
While you do all the right things to keep your computer secured, password protected and your data backed up, don't forget to keep your computer physically secure while you work and when you travel. If you find or someone gives you a USB drive or other device and you haven't used it before, try it on a computer you don't care about, confirm with someone else (like your office IT staff) that it's safe, or better yet, just don't use it. Most people don't transfer files via USB these days any more anyway.
If you find a USB drive discarded somewhere, don't bother with it. That sounds silly, but considering almost half of us would actually use a USB drive we found on the ground, it's worthwhile advice.
For more on the USB Killer though, how it works and why it was created, you can check out the links below.