Go figure

There were two guys working for the city. One would dig a hole and the other would come behind him and fill the hole. They worked furiously; one digging a hole, the other filling it up again.

A man was watching from the sidewalk and couldn't believe how hard these men were working, but couldn't understand what they were doing. Finally he had to ask them.

He said to the digger, "I appreciate how hard you work, but what are you doing? You dig a hole and your partner comes behind you and fills it up again!"

The digger replied, "Duh, the guy who plants the trees is sick today."