To make a pickle glow, insert a thick copper wire into each end of the pickle. Cut a power cord, and strip the insulation off the wires at the end. Cut the live wire about 6 inches shorter than the ground wire, then wrap the wires together. Connect the power cord to the pickle wires with jumper cables. Plug in the power cord.
As explained by Marc Cyran, the pickle glows a yellow color due to the sodium ions in the pickle. The pickling process involves soaking a vegetable in a salt solution, so pickles are full of sodium ions. The pickle continues to glow until it completely dries out, at which point it may burst into flames or explode.
The Isaac Exploratorium explains that the above-described method is extremely dangerous and suggests introducing a ground-fault circuit into the system to improve the safety of the glowing pickle. The Isaac Exploratorium also says that even with the ground-fault circuit, it is a very bad idea for anyone to touch the pickle or any of the exposed wires. To change the color of the glowing pickle from yellow to pink, try soaking a regular pickle in a potassium chloride solution for a week before plugging it in.