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This article contains information relating to a hoax. According to Cambridge dictionary a hoax is "a plan to deceive a large group of people; a trick."
Disco Demon also known as Diabeł-z-Dyskoteki (pl. Devil from the Disco) was a Polish hoax demonic cryptid that was the source of many urban legends in 1980's and 1990's, espiecialy in the Ostrow area.
The creature was described as a shapeshifter to some degree. It could turn itself into either one of it's two forms - a human and a demon, and was possibly fully sentient. It could however be distinguished from other people by the fact that it smelled of sulfur and possessed hooves, even in its human disguise.
One of the creature's supposed attributes was it's car. In most version of the story it was described as completly black BMW without a license plate and tiny horns instead of car mirrors. It would usualy be seen in a bar parking lot. The creature would walk out and ask a random person about the time, and after it would receive it's response the demon would kill them, or some other person at the party.
From a political point of view, much like Poland's other demonic cryptids such as the Black Volga, the Disco Demon was most likely created as a hoax to scare people away from going to raves, parties and bars. The same thing applies to the Sataniści.