I think I'm listed as the wrong generation, because most of this was after my time.
Bubble gum,
hats,
shorts,
hugging
But... students protested the last two. Shorts were banned because authority figures thought they were too summery and would make students feel like they were still free to act as though they were on vacation. Male students noticed that female students were still allowed to wear short skirts, and decided that the ban on shorts was sexist. One day, all of the popular and influential male students, including the macho jocks, came to school wearing skirts. The rule was changed shortly after so that shorts were allowed again.
When they tried to ban hugging, the popular female students were the first to react by spending their time between classes hugging each other very visibly in front of any authority figures who happened to be observing. At first, they would get in trouble for it, but the less popular students followed the example until the hallways were the location of a massive schoolwide hug-in every time the bell rang. When even the geeks were in on it, there really wasn't much the teachers could do. They weren't going to suspend straight-A students who had never had any disciplinary problems before. If they had enforced the rule, they would have suspended nearly EVERYONE in the entire school. That rule was eventually changed.
See, the popular kids who made my life hell were actually good for something. They were the first to feel entitled and empowered when the rules started to get oppressive, and they were confident enough to take risks.