Most people never stop to think what makes us laugh. It is the "fear of loss of dignity, social embarrassment, exclusion from the group, being fooled/exploited, death, injury, or sex. The more anxiety-prone the subject is, the better it is as a subject for humour."*
Why do it then, why not just forget about laughter?
Well nothing dispels anxiety faster and helps oneself and others around them relieve stress and become more attentive, alive.
Humor therefore is a weapon, it can be used for good and evil. Like all weapons, one must respect its potential for damage.