A person usually followed by a hoard of carrots, screaming as they march to their carroty doom. A Sidni usually enjoys long unflinching staring contest which can last for weeks on end due to their two glass eyes, they rarely need to blink, and a quick slurp from their tongue will usually suffice. Often likened to a zombie eating a cat, the Sidni's imagination is usually running rampant in a slew of made up words, and random thought-tangents.
I saw this Sidni once, and immediately remembered my cat followed by the memory of the stink of rotting flesh, and a sudden triggering of the gag reflex.
Don't ever send your cat outside to scout for zombies.