Human residents of the island make night potato vodka whenever they forget what a bad idea this turned out to be last time someone tried it. The usual method is to capture and kill night potatoes, then ferment them – usually in some sort of bucket. The bitterly cold weather in winter makes it easy enough to freeze off the excess water. What results is often excellent for starting fires, and likely to leave a drinker mad, blind, glowing, or all three.
This is as nothing when compared to the night potato vodka made by night potatoes. Night potatoes are not known for eating each other. However, sometimes a night potato dies of natural causes, and this will go unnoticed by their comrades until decay starts to set in. There is a particular sort of fungi that grows on the eyes of decomposing night potatoes, and it is from this fungi that the night potatoes themselves brew their vodka in tiny receptacles.
Whether it is the naturally glowing eyes of the night potatoes that result in the fungi also glowing, or whether it is the fungi that glow and the night potatoes gain their eye glow through drinking it, is hard to say. My suspicion is that this is a more complex and circular relationship.
If a human has ever partaken of the vodka made by night potatoes, none has ever survived to tell the tale. It does not suggest itself as an especially survivable experience but no doubt at some point, someone will be willing to test this theory – either for science, for poetry or in the hopes of finally escaping from the island.