A suicide cord is a length of power cable with a plug for an electrical outlet on one end and nothing on the other end, simply terminating in two or three bare conductors. As you can probably imagine, this looks like a particularly dangerous piece of equipment. Of course, it's not intended to be plugged in without the conductors safely attached to something, but at first glance it might appear to be some sort of torture device.
Suicide cords are useful instruments when bench-testing electrical equipment intended for industrial applications. Many industrial devices are intended to be mounted in an enclosed electrical panel rather than plugged into a wall outlet, like a lamp would be. Electrical outlets are useful for devices that may be unplugged and moved at the owner's convenience, but they take up entirely too much space and have expensive safety features that are not necessary for industrial applications. Instead, devices mounted in an electrical cabinet are typically wired up with insulated wires attached to small terminal blocks rather than bulky molded-plug cables and shielded outlets. While this is potentially more dangerous, electrical cabinets are intended to be opened and maintained by qualified personnel only, who know how to take appropriate safety precautions.
The suicide cord comes in handy when bench-testing the equipment, either before installing it or while troubleshooting or performing maintenance on it. Unlike consumer electronics, these devices do not have a molded plug permanently installed, since they are intended to be hooked up to simple wires in a panel. The suicide cable acts as a compromise here, allowing the molded-plug connection for the test bench's standard electrical outlet on one end and the bare conductors for the device's terminal block on the other. The device should obviously be firmly attached before plugging in the cord.
Suicide cords are typically made by simply cutting off the cord from a broken appliance that would otherwise just be thrown away. The end is then trimmed and the insulation stripped to expose the bare conductors. in the absence of broken appliances, however, sometimes it's necessary to make your own. This is usually just a matter of taking a 2- or 3-conductor cable and screwing a replacement outlet plug (available at any hardware store) on the end. Be careful to observe standard wire coloring! Neutral wires are white or blue, hot wires are black or brown depending on whether you're using NEMA 15 or IEC 320 standards. Ground will be green or green with yellow stripes. If you're using a polarized plug (usually a good idea), the neutral prong is the wider prong.