Jones is driving past the state mental hospital when his left rear
tire suffers a flat. While Jones is changing the tire, another car
goes by, running over the hub cap in which Jones was keeping the lug
nuts. the nuts are all knocked into a nearby storm drain.
Jones is at a loss for what to do and is about to go call a cab when
he hears a shout from behind the hospital fence, where one of the
inmates has been watching the whole thing.
"Hey, pal! Why don't you just take one lug nut off each of the other
three wheels? That'll hold your tires on until you can get to a garage
Jones is startled by the patient's seeming rationality, but realizes
the plan will work, and installs the spare tire without incident.
Before he leaves, he calls back to the patient. "You know, that was
pretty sharp thinking. Why do they have you in there?"
The patient smiles and says, "I'm in here because I'm crazy, not
because I'm stupid."