According to a new study, zombie fads peak when society is unhappy.

So when there’s cultural dissatisfaction and economic upheaval, the numbers of zombie movies, television shows, and video games increases.

We also see more “zombie mobs,” where people dressed like zombies gather, stagger around, and dance. As of last year, zombie mobs had been documented in 20 countries, with the largest one drawing more than 4,000 participants in New Jersey. (Yahoo News)