Two guys were working for the city. One would furiously dig a hole, then the other would come behind him and quickly fill the hole. They were drenched in sweat.
A man watching from the sidewalk couldn't believe how hard they were working, but also couldn't understand what they were doing. Finally he said:

"I'm confused. You dig a hole and then your partner comes behind you and fills it up again!"

The digger leaned on his shovel and replied, "Oh yeah, it must look funny. You see, the lazy jackass who plants the trees is sick again today!"