Arising from an Urban legend of a defender who would go out of his way to right wrongs, this term has now become part of the common vernacular of Southern California specifically in the Los Angeles, Beverly Hills, Santa Monica regions.
A. Verb (used with an object)
1. To relentlessly pursue justice and retribution for a perceived harm.
2. To protect the interests of yourself or those close to you by haranguing those who do harm even if that harm was unintentional.
3. This action can be positive or negative depending on whether one is on the giving or receiving end.

B. Noun:
1. Verbal maneuver or quality designed to elicit a personally favorable response from another; often clever with use of Socratic questioning or deductive devices which put the person on the receiving end at a distinct disadvantage.

The two states of being are as a human being, or a hungry ghost. Semi-regularly you need to ask yourself which you are. Sometimes it is human. Others, alas, it is hungry ghost.

The hungry ghost seeks validity outside of themselves. Someone pining for an indifferent ex is a hungry ghost. Someone who arrives alone at 6:30 on Saturday night to a pub is probably a hungry ghost. Obsessive checking of mobile phones, chat sites or networks are clear signs that one is a hungry ghost.

The best thing to do is just stay home and ride it out. Read a book. Find some good clean fun.