What does "rue is a cat" mean?

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baev_os#1090 wrote:

One day Rue was trading with someone, trade went wrong and he was called a cat without fur, you know, like those Sphynx cats.

And, after reviewing the images and info about the breed, many people in his chat actually found immense similarity between Rue and those cats.

So, to this day they cannot decide whether he is a cat or a human pretending to be a cat, or a cat pretending to be a human. It is uncertain.

"Rue is a cat" is just one of his viewers expressing his position about that question.