It was dusk time when a man had a flat tire right in front of a mental health hospital. After unscrewing the four nuts of the flat tire, he noticed that a hospital patient is watching him from over a nearby embankment. He managed to step on the hubcap in which he had carefully placed the nuts. To his dismay, the nuts went flying into the grass on the side of the road. So he got on his hands and knees and started searching in vain for the nuts in the semi-darkness.A few minutes later he heard the mental patient chuckle, so he shouted at him irritably, „What are you laughing at?“The other guy explained: „Well, you have three other tires, each of which has four nuts… If you were to take one nut from each, you’ll end up with four tires being held in place with three nuts per tire. This should be safe enough for you to drive to the next town over, where you can buy a new set of nuts.“Embarrassed, the poor car driver couldn’t help asking, „How come you’re so clever and you’re in a mental hospital?“The patient replied, „I may be crazy, but I’m not stupid!“
