Affiliate Marketing Secrets

So last week, a friend of mine was caught with alcohol at one of our High School football games (stupid I know), and we’re both 18. I wasn’t drinking, and didn’t get in trouble, but my friend was found out because the Principal said “Hey, give me that bottle” (we’re not supposed to have bottles from outside while in the stadium. The stadium is non school-affiliated, either.), my friend handed it over, and things went on from there.
So… did my friend have to give him the bottle? Because we’re off school grounds, does he have any right to demand that he see it?
And also, if I were to bring in a bottle during the next game with say, urine, in it, is it:
1. Legal to have a bottle of urine in public, and
2. Legal for him to demand to see my bottle?
Thanks! 🙂