那只叫冬菇的猫
[nèi zhĭ jiào dōng gū de māo]
'The cat called Black Fungus (冬菇)' Winter mushrooms are brown mushrooms grown during the colder seasons. The mushroom is blackish-brown in appearance and has a good smell. So this username is given by people for its uniqueness as it connects a random object (mushroom) with an animal(comic), hence giving off an endearing vibe.