I've only read a few of the stories in the book so far, but one of them I found the premise to be really interesting. The story titled "Red Card" was about a town which gave out a few red cards and a revolver anonymously to citizens. These red cards entitled the holder to shoot anyone, for any reason, and face no consequence. You can hold onto the cards for as long as you like, and you can use it whenever you felt as well. However, you're not supposed to tell if you hold one of these red cards, and when you use it, you must turn it over to be re-issued.
After reading the story I was thinking about who I would use a red card on. A pretentious classmate in college? A horrible professor? A bad driver or waiter? Eh, who knows. I bet if I held a red card I would just sit on it for years and never use it because I'd be too nervous that I would later regret using it on the person I had chosen.