A guy watches two men working
The first digs a hole in the grass verge, and the second one comes along and fills it in.
The first chap walks several yards on and digs another hole, and sure enough his mate comes along and fills it in.
After the 4th hole the guy watching can stand it no longer. He goes up to the workmen and says, "I'm really impressed at how hard you are working. But what are you doing?"
"Ah," says the first man, "we're from the highways department. There's usually 3 of us, but the guy who puts the tree in the hole called in sick this morning."