Known as the Straw Hat Riot of 1922, it was a series of protesting and rioting around New York City. Not for equal rights between men and woman, or against racial discrimination or police brutality or LGBT rights, no this was for what at the time was seen to be a travesty. It was about men wearing straw hats past the unofficial date that was seen as socially acceptable.
The date in question was September 15, after this time, men apparently should no longer be seen wearing straw hats in public. And though it may seem silly now, these riots ended up in numerous arrests and multiple injuries.
One of the main problems was this date was arbitrary, it seemed to shift year by year. Earlier the limit had been the 1st September then it was a mid-month date. Any man seen wearing a straw hat was at the very least going to be mocked in the street, in fact, youths started to knock off the hats and stomp on them. And this tradition was even supported by the local media, newspapers would let people know that the date was approaching and that men needed to switch back to felt or silk hats.
What happened was a group of youths decided to get in early on the stomping and start off the tradition on the 13th, in Manhatten. They were removing and stomping hats worn by factory workers without much of an issue until a group of dock workers decided they did not like their hats being stomped on. This escalated into a full out brawl with traffic being stopped on the Manhattan Bridge because of it.
Then gangs of hat stompers started to prowl the streets with sticks and bats, beating down pedestrians who resisted. Reports said these mobs were over 1000 strong, and there were also reports that the police were much too slow to respond which caused the riots to get much worse. The tradition died out after some time, most likely due to Panama hats becoming quite fashionable during the 1930s.