Waldensian-Christians in the medieval period were accused by propaganda of commiting sodomy with a demon in the shape of a cat and that they had to commit the Osculum infame by kissing the ass of said cat-demon.

It was also common in medieval Germany to belief that the german word for heretic "Ketzer" had it's origin in the german word for cat "Katze" and was refering to people who did similar things with cats as the Waldensians were accused of. In truth the word "Ketzer" goes back to an italien word for the followers of Catharism, but that wasn't widely known at the time and so many allegories were made of heretics and cats.