In July 1518, residents of the city of Strasbourg (then part of the Holy Roman Empire) were struck by a sudden and seemingly uncontrollable urge to dance. The hysteria kicked off when a woman known as Frau Troffea stepped into the street and began to silently twist, twirl and shake. She kept up her solo dance-a-thon for nearly a week, and before long, some three-dozen other Strasbourgeois had joined in. By August, the dancing epidemic had claimed as many as 400 victims.
They have all come down with the "dancing plague".
https://www.history.com/news/what-was-the-dancing-plague-of-1518
In July 1518, residents of the city of Strasbourg (then part of the Holy Roman Empire) were struck by a sudden and seemingly uncontrollable urge to dance. The hysteria kicked off when a woman known as Frau Troffea stepped into the street and began to silently twist, twirl and shake. She kept up her solo dance-a-thon for nearly a week, and before long, some three-dozen other Strasbourgeois had joined in. By August, the dancing epidemic had claimed as many as 400 victims.