There is nothing cooler than a glowing yellow pickle (except maybe when someone makes a sexually suggestive joke about it). Of course it is even better when someone uses it to show of how something else works.
MIT professor Vladimir Bulovic, used an innocent, yet soon to be heroic pickle to show us how Organic LEDs actually work. What happens is that they pass electrons through the organic matter to charge the substance. As positive and negative electrons collide they release photons in the form of light.
The demonstration is a very simplified showing of how this works (as the whole pickle is used to represent a single element in a normal OLED display but does show us how the principle works and what's more is pretty cool.