The text plays on the double meaning of the word 'role.' It refers to a person's function or part in a particular situation, and it also implies acting a part in a play or film. However, the humor also derives from the unexpected twist of being important as a 'negative example,' which is typically not seen as a positive thing. This creates a form of wordplay based on the expectations associated with the word 'important role.'
You have an important role as a negative example .