This phrase is not a slang term, but a literal question that translates as 'What animal is this cat?'. It seems nonsensical because a cat is a known animal. It could potentially be used in a humorous or sarcastic context to emphasize the odd or surprising behavior of a cat.
Examples
- Spanish: Mi gato acaba de abrir la puerta por sí solo. ¿Qué animal es este gato?
- English: My cat just opened the door by itself. What animal is this cat?