One of my biggest pet peeves goes something like this.
While talking about some complicated issue (like free will, for example), one participant makes some distinctions between words and ideas in order to elucidate some important points in the conversation.
They do so usually in response to a comment which either confuses two uses of a word, brings to mind a conceptual distinction, or otherwise indicates a bifurcation of ideas which are relevant to the conversation.
So, you articulate the relevant distinctions in order to clarify the various positions, uses, etc. And then someone (often the person responded to) says “that’s just semantics.”
Well of course it is! It does have to do with the definition or use of a term. It is indeed hair-splitting of terms and ideas. That is precisely what making fine distinctions in order to elucidate idea is about, and pointing it out is nothing but demonstrating that you are not really capable or interested in fully participating the discussion being had.
This comes up when I talk about what atheism is, especially in comparison with agnosticism. But is happens quite frequently, and it annoys the fuck out of me.