It drives me mad when people say something in a debate or argument that makes no sense, or that blocks progress, or that just derails the entire thing - and one has no way of, as it were, deeming their strategy unacceptable.
For instance, "well, I don't know about that."
Them: <bunch of ill-founded nonsense, some of which they've heard somewhere and a lot of which they just made up>
Me: <Fact one, cited. Fact two, demonstrated. Fact three, logically derived from facts one and two and independently supported by numerous subject-matter authorities>
Them: Well, I don't know about that. I'm just saying that that's what happened to my cousin and she hasn't had a moment's peace.
At this point, I want an otherworldly spirit to appear, preferably taking the apparent form of Miriam Margolyes, and say, "No, you don't know about that, do you? But you've just been told about it. So now you have to take that on, and incorporate it into your worldview. Otherwise you're a self-deluding fuckwit, aren't you? Thank you. Continue."
So, what other argumentative phrases or positions would trigger the apparition of Miriam?