I agree that adult material should not be available to kids. This is why it has been placed in adult book stores or other adult shops. You can buy some adult magazines elsewhere but they are kept in a separate area so that kids do not look at them.
I believe that giving those a foothold in banning anything is a foothold down the wrong path. There should be safeguards in place to follow if one student or their parent finds the material to be offensive. Banning it because your offended is not fair to others. Let everyone make their own opinions on what to read or not to read. If the person is under age then their parents should monitor what they are reading.
I know I"ll be criticized for saying this, but I feel that there should be a rating system for books, as they do for movies. When choosing what book I want to read. I want to know if it has any graphic details, like sex, or swearing. If you choose to read those kinds of books, then so be it. I should be able to choose BEFORE I start reading a book, not after!