I went to school in the era when short hair was mandatory, but strictly short back and sides. When a couple of guys arrived with "crew cut / skin head" styles it didn't go down well to the point that they had to play rugby with their caps tied on to their heads,
Stupidly dangerous when you now think about it but it actually happened. - and stopped too many others copying the style. They may have been the best days of your life, but that was only if you survived.