Speaking of fads... and Tzfatim

"Dancing mania (1374) — Northern European religious fad in which people danced uncontrollably for hours. They formed circles in streets and churches and leaped, screamed, and rolled on the ground, often shouting that they were possessed by demons and begging said demons to stop tormenting them.

Caused by nervous hysteria and/or the wearing of pointed shoes."

(Bellwether, Connie Willis)

Now I understand where the behavior of Tzfatim (many of whom are French-speakers wearing pointed shoes) comes from. And, as the book by Connie Willis suggests, to start a fad, one needs a bellwether: a sheep that leads the rest of the herd.