To dream that you are telling a joke, suggests that you are not being taken seriously and as a result you are feeling frustrated. On the other hand, you may not be taking an issue seriously.
To hear a joke in your dream, signifies that you are doing something pointless. It may also mean a release from tension that had been bothering you. Also see “Practical Joke.”... My Dream Interpretation
A joke works because it shows situations in a new perspective. Perhaps you should re-examine your rigid perspective. Don’t take life quite so seriously, and let the soul be a source of joy.... Little Giant Encyclopedia
Psychological / emotional perspective: Emotionally, a joke can bring about a release of tension and a bizarre occurrence in dreams which causes amusement can do the same.
The aspect of our personality which shows itself as a joker has the same meaning as a jester – someone who can make us laugh at ourselves and arouse a sense of the ridiculous.... Dream Meanings of Versatile
Material aspects: A joke in dreams can be an image presented in an odd way. It is as though the mind develops the oddity in order to have us remember what it is attempting to present.... Dream Meanings of Versatile
A dream featuring this card is warning you that your idleness could make someone else richer. Get busy - if you let someone else take what’s yours, you will only have yourself to blame.... My Dream Interpretation
As is often the case in waking reality, jokes often cover up something far more pertinent in your dreams. They are also a way of calling attention to things that you might otherwise overlook. Consider the subject of the joke, and the peripherals in the dream, for more insight.... The Language of Dreams
If you dreamed of playing a practical joke on someone, your success will be delayed.
If you were the subject of the joke, you will have control over a new situation. Be wise in using this unexpected power, because if you try to go too far and take advantage of others, it will backfire on you!... My Dream Interpretation