Final answer:
The behavior of rowdy fans yelling obscenities at a football or soccer referee after a controversial penalty has been called is best described as Mob mentality.
Step-by-step explanation:
The behavior of rowdy fans yelling obscenities at a football or soccer referee after a controversial penalty has been called is best described as Mob mentality. This term refers to a situation where a group of individuals engage in impulsive and irrational behavior due to the influence of the crowd. In this case, the rowdy fans are acting collectively and expressing their dissatisfaction in a disruptive and aggressive manner.