"Caution"

How does one take seriously this warning sign?

We learn in our driving instruction and in the third-grade that yellow signs imply caution, or in this case "caution." I think the producers of the sign think like my old coworker and his favorite story from truck driving school.

One day I told a joke that went like this:

Two guys went to truck driving school, they graduated and got their first job together driving a big-rig. On their first trip out, they had to take a detour and along the way passed a sign that read:
"Danger Low Bridge Ahead - 10' 11""
They continued driving until they came to another sign stating,
"Danger Low Bridge Ahead - 10' 11""
They drove on until they came to the bridge itself, it had a sign too, it read:
"Danger Low Bridge - 10' 11""
They got out of the truck and measured the height of the trailer at 11' 3".
"What do we do?" one said to the other.
The second young trucker looked around a bit and finally said, "Not a cop in sight, let's go for it!"

This is not the funniest joke in the world. The delivery was pretty good, but not hilarious. However, one of my coworkers looked puzzled.

After a few moments passed, he looked up at me and said, "There's no way that truck is getting under that bridge!"

That was much funnier than my joke.

Thanks to my friend Steve for the picture.