一个倒霉的司机正在精神病院围栏外换一个瘪胎。就在他卸下轮胎时，不小心把四个螺母全都碰进了深深的排水沟里。他被困住了，开始惊慌，因为没有办法把备胎固定上去。
一个一直在观看的病人从围栏里面喊道：“嘿，你为什么不从另外三个轮子上各取一个螺母呢？这样你就有三个螺母可以装在备胎上，这足够支撑你开到修车铺了。”
司机听了惊讶不已：“太聪明了！你能想出这种办法，怎么会在这里呢？”
病人说：“听着，我在这里是因为我疯了，不是因为我蠢。”
A driver is changing a flat tire right outside the fence of a mental asylum. As he removes the wheel, he accidentally knocks all four lug nuts into a deep storm drain. He's stranded and starts to panic because he has no way to secure the spare tire.
A patient watching from behind the asylum fence calls out, "Hey, why don't you just take one lug nut off each of the other three wheels? That’ll give you three nuts for your spare—enough to hold it until you get to a service station."
The driver is amazed. "That’s brilliant! Why are you in there if you can come up with a solution like that?"
The patient replies, "Look, I’m here because I'm crazy, not because I'm stupid."