What is mob mentality?

Answer 1

Mob psychology, or mob mentality as it is informally known, is the idea that we act differently in a crowd because we loose our sense our individual identities and we desire harmony within the group so we do not protest even when actions or sentiments are extreme.

Answer 2

Attempt at answerIt is two or more people who take justice, as they see it, into their own hands.

Actually, I believe mob mentality has more to do with the way people act when they are in a group as opposed to the way they act as individuals and less to do with any sense of "justice"

Mob mentality does not have to do with the individual or group taking justice into their own hands. Mob mentality deals with the spread of emotion, good or bad, among humans when they are in a medium to large size group. typically in popular culture you hear about mob mentality (essentially herd behavior) in the context of people getting trampled in events such as black Friday shopping. this is usually a spread of panic through the crowd causing them to frantically rush toward their in-store goal, ignoring anything in their way.