The Dancing Plague of 1518 in Strasbourg, France, saw 400 people dance uncontrollably for a month, with many dying from strokes and exhaustion. While some theories suggest spider bites or ergot poisoning, it is widely cited as a primary example of mass hysteria. The hosts argue that modern mass communication acts as a force multiplier for these types of collective delusions, allowing "symptoms" to spread faster than in the 16th century.