I was once in a boring work presentation. The presenter was explaining in detail a concept that didn't really need more than a few sentences to get across. My mind started wandering to what I would do after the collapse. I imagined myself on a farm somewhere, with self-sufficiency and solar panels and an alarm system and a whole field of crops. I imagined how troubling that would be, because hungry people would come to take my crops. I would have an alarm system, but what I am supposed to do? I can't blame them because they're hungry, but I also can't just let them take my food. I imagined to myself this guy reaching for one of my tomatoes, and then me shooting a warning shot, and the tomato blowing up that he was reaching for, and his expression of shock.
I then remembered that I was in a work presentation with several minutes having gone by and I was supposed to be paying attention. I started listening again, and found out that the guy was still talking about the same concept as when I'd originally wandered off. I left that job pretty shortly after that.