In waking life, many jokers, comics, comedians and humorous people are sad people. They pretend to be cheerful and happy because of the deep sadness within.
If you dream of a joker, it means your brain is trying to tell you that you are in conflict. You are sad, while pretending to be cheerful and happy. In waking life, you should pay attention to people around you, who act like jokers. These people are dangerous. They act in contrast to their behavior. They can pretend to be happy, and your friend, while in their hearts, they are bitter enemies.
