Interpretation
Lighten up! When the Joker shows up it is an indication you are taking life too seriously. Have more fun, take time to play, be a child, or see the humor in whatever it is you are dealing with.
How to Read This Card Reversed
When the Joker is reversed it may be that you are not taking life seriously enough; everything is a joke. Or, it may be conveying that the issue you are looking at is not at all black or white, rather it indicates both sides have some merit.