Old joke.
Man gets a flat tire outside an insane asylum. He starts to remove the old tire and puts the lug nuts in the hubcap. He places the new tire and then accidentally steps on the hubcap and sends the nuts flying. They all go down a storm grate.
While he was working he had an audience of inmates watching him. Suddenly one of the patients yells, "Take one nut off of the other three wheels. You can make it to the next garage if you don't drive too fast."
The man thinks it over and takes the advice.
"Thanks, that was a great thinking."
"I'm insane, not stupid."