I think it's GOOD that they banned them. Think of all the lurid sexual activities that were prevented by not allowed teens to wearing cheap petroleum-based jewelry. Ha, I say! I would like to see some 14 year old girl give some guy a blow job when she doesn't even have the correct color-coded bracelet. Imagine, if you will, this heart warming scenario:
Boy: I wish I could have some under-aged sexual activity in a complete rejection of the solid moral foundation provided by my parents and professional educators.
Girl: I would be willing to give you oral sex. Is that the kind of under-aged sexual activity that you mean? I know our parents and professional educators say it's wrong but I am a rebellious teen and therefore enjoy contravening their directives.
Boy: Thank you. May I break the ___________ color sex bracelet so we can commence with this illicit sex act?
Girl: Alas! The school, in the spirit of well-reasoned social engineering by our professional educators, have banned wearing these so-called "sex bracelets."
Boy: But that means you can't give me oral sex!
Girl: It's true. They have thwarted us.
Boy: I have a joint and some beers. Want to get high instead?
Girl: Yes! We don't need bracelets for that!