Although we don't admit it, we have probably all had one of those moments where somebody is blabbing on profusely about something we have no interest in at all. You find yourself thinking of what you're having for dinner, or what time you need to wake up tomorrow to make sure you don't miss that lecture or meeting, then soon enough they notice you're not paying attention. It's easy to tell when that happens, by the way. So, to prove that you are listening, you could simply nod like a nodding dog and affirm what they said. Or, if you're a rude person, you can tell them to "pipe down" and get a life. However, for all you polite people, what happens if they expect an answer from you? If, for example, they have assessed something and expect you to assess it in return, how can you escape? The simple answer is to topic shift. Shifting topic is, however, rather difficult to do, unless you use a simple and effective device called a figurative expression. You may know them as idioms, or idiomatic expressions, but whatever you call them, they actually do have a purpose beyond bamboozling non-native English speakers. You can use them to escape the graps of that hideously tedious topic you dread. Take this as an example of how to use them:
A: Oh, poor Liv, she was such a lovely woman. I remember when we used to play bingo together.
B: Well, every dog has its day.
A: That's true I suppose.
B: Yeah.
A: So, what are you up to tomorrow?
Of course, your idiom has to be relevant, but as long as it is then you can pretty much get away with it. Similarly, these figurative expressions can be used to exit a conversation before it gets to the point of boredom. So, take note!
c.f. Drew and Holt (1998)