Tell a joke

There was a man that would often park his Toyota Highlander in front of his office. There was also a certain mad man who often frequented that route. One day, the mad man noticed the Toyota parked with 4×4 at the rear end of it. He looked for a nail and wrote equal to 16 beside the 4×4.
The man came and saw it and asked who did it, he was told that it was a mad man. He smiled and used paint to clean what the mad man had written.  The next day he parked his car on the same spot and the mad man came and saw it. He said to himself, I thought I answered this question yesterday, I must be going mad.”
So he answered it again! This time when the owner of the car saw it, he decided to customize equal to 16 on his car. But when the mad man saw that he had done that, he decided to write very good and a Nike sign beside it.

Vera