A truck driver was doing his usual delivery to the Mental Hospital.
He discovered a flat tire when he was about to leave.
He jacked up the truck and took the flat tire off.
When he was about to replace the flat tire with the spare tire, he accidentally dropped all the nuts into a storm drain. Realizing he can't fish the nuts out, he starts to panic.

A patient walking by asks him what happened. The driver told him his problem.

And the patient said "Can't even fix such a simple problem... no wonder you are destined to be a truck driver..."

"Here's what you can do, take one nut each from the other 3 tires and then tighten them on to the spare. Then drive to the nearest garage and replace the missing ones, easy as that!"

The driver was very impressed and asked:

"You're so smart but why are you here in a Mental Hospital?"

Patient replied:
"Hello, I am here because I'm CRAZY, not STUPID!!"