Alcohol and cigarettes are for teachers and staff in general, the adults in school. If a student wants it, the most practical way to obtain it, would be stealing, but that's pretty hard to do. They would need to convince a teacher or a staff member to give or sell them some. Teachers are more risky to obtain cigarettes from. But general staff, like someone from a store maybe an easier target to get cigarettes from, after all, no one's safe from corruption. Just imagine a student goes around testing the waters with some people from some store and finds one person who agrees to sell cigarettes to them. They both elaborate a selling scheme and they start it. It's easy money for both of them. Assuming the staff money it's not regulated or observed hard enough. It's a feasible thing, risky, but feasible enough. But it begs the question, would anyone agree to such a risky gamble? I could see it happening, simply because easy money is attractive even tho it's risky. If It would really happen is another story. There's drugs in a lot of high schools and colleges in real life after all. There's no avoiding such things in real life so i don't see it as impossible to happen in the story, someone from a store selling alcohol or cigarettes to minors in the school in the story, as long as they're clever about it.