"See no evil, hear no evil, speak no evil". (Read here: http://en.wikipedia.org/wiki/Three_wise_monkeys)
In many interpretations it can be seen as a way to avoid spreading evil. Do not listen to evil things so they do not influence you. Do not read things that are evil or look upon evil things so they do not influence you, and lastly do not repeat verbally evil things so they cannot be spread about.