It's a combination of two words:
* "Hani" (嫌い) - meaning "hate" or "dislike"
* "Neko" (猫) - meaning "cat"
While it's literally translated as "hate cat," it's often used humorously or ironically, especially online. It can be a playful way to express affection for a cat, similar to how people might call their pet a "little monster" or "furball."
However, it's important to note that in some contexts, it can be interpreted as a negative term, especially if used in a serious or angry tone.
Always consider the context and the person you're interacting with to determine the intended meaning of "haineko."