When we moved to England, I went to the working-class neighborhood grammar school. It didn't have the hoity uniforms of the public/private/whatever-you-call-them schools, but there were, nonetheless, "understandings" of what one was supposed to wear—some codified, many not. And my end-of-the-seventies scruffy American eight-year-old non-chic did not accord with these "understandings". And my scruffy American eight-year-old non-chic brain did not
understand these "understandings". So I wore my prized Dallas Cowboys jersey to school—a lot—like almost every day.*

This presented a conundrum for the administration: there was no rule explicitly forbidding it, yet this behavior certainly could not continue. So they made a new rule:
No shirts with writing or numbers.
And so, my New World individualistic spirit was quashed. I never again wore my Dallas Cowboys jersey to school but relented to their post-imperialistic peevishness and fell in knicker-clad line. But I vowed, some day my crass American freedom flag would fly again. And so it did. And so it does.
(Well, actually, maybe not. In my adult life, I tend to favor shirts without writing or numbers. Did I internalize their stricture?)
* Yes, even as a child, I was prone to extreme repetition in my attire. (As a wee lad, I had a blue baseball cap with a yellow chick on the front that I deeply, deeply loved. My mom finally had to hide it from me because I wore it so relentlessly it risked fusing to my scalp.)