I had some teachers try to pull that shit. I just went and got a doctors note. It's even stupider than not letting people drink pop in class. Like okay. I'll just chug a whole can of coke in under 5 minutes and be burping - even with a closed mouth, you can hear it, and trust me I trained it to be as lout as it could - all through the class. Kinda reminds me of when the school tried to ban kids from bringing cell phones onto school property. All the parents came in and brought in some paper or got special permission of some sort, so the school relented (I didn't have a phone and was over 16 at the time so my mom wouldn't get involved in school or legal shit, so I don't know exactly what went on)