So you're playing a game with fancy dialogue options and notice that maybe the responses you're given look a little too similar. Or maybe the NPC's response to your answer is just too much of a non-sequitur for your liking. You may have just encountered the Un-Question, a question which, no matter how you answer, will end up with the exact same NPC response. It may be due to lazy programming, or be intended to demonstrate the NPC's ability to listen, but you know you're in a conversation which gives you no real options.
Hello, Unknown Troper. You'll need to get known to lend a hand here.