You must not know this old joke....
A man in a business suit gets a flat tire in front of a mental hospital. He gets out and starts to change the tire. He lays the lug nuts on the street, and before he can put them back on, the wind blows them down a drainage ditch.
Now he has no lug nuts for this wheel, and he starts to get nervous when he sees a patient from the hospital staring at him from behind a tree.
The patient speaks up, and says, "Why don't you take one nut from each wheel and put them on this wheel, and then you have at least three nuts on each wheel until you get to a garage?"
The man in the suit realizes how brilliant this is. He turns to the patient, points at the hospital, and says, "That's really good advice. Why are you in here?"
The patient says, "I'm crazy, but I'm not stupid."