Can you please explain some of the usages as well?
- Anybody can ask a question
- Anybody can answer
- The best answers are voted up and rise to the top
It is a compliment - what is there [about the thing we're discussing] that someone wouldn't like? Nothing, right? So for example, discussing a vacation possibility:
Language being what it is, people sometimes use it sarcastically to emphasize how much they dislike something:
Without context nobody can know which meaning is intended so please edit your question to include where you heard it and what you thought it meant (from tone of voice and reactions of others.)
Generally used rhetorically, it literally means "What [about this topic] would someone dislike?" and generally implies that the answer is "nothing" (nothing not to like, ergo, everything to like). However, like many well-known English phrases, it can be used to imply that the answer is the opposite of the "usual" answer, namely that there's everything to dislike.