There are many kinds of viral marketing. What they have in common is that they are worth sharing because they create emotion, are considered important to know or because the viral itself is a product or service.
This viral makes us laugh, cry or become angry, which results in us wanting to share the message with our friends, family and others. Successful virals touch upon a couple of emotions that strongly connect with viewers such as amusement, anticipation and excitement. Negative emotions, such as guilt, sadness, and anger, seem to work less well.