Albert is driving down a remote road in the mountains.
After a curve he notices a street sign that says, ‘Watch For Fallen Rock’.
A couple of miles of careful driving later, Albert spots some pebbles on the road and stops to pick up a few.
Arriving in the next town, he walks into the road maintenance office.
Placing the pebbles on the counter, Albert says to the official: “Here are your fallen rocks. Now where’s my watch?”