Children should be SLOWLY exposed to adult entertainment to prepare the from the real world. If not, then children will grow to be ignorant. Once again, children should be SLOWLY, or else it can be too much at once. If sheltered from adult entertainment, then they will want to see it even more.
If below 18 children are allowed to adult entertainment, then it can lead to a social dilemma and these children don't know what is right and wrong in adult entertainment. So even below 10 years of age children will also exposed to adult entertainment. They will take out the experience towards any one they met. So it will be dangerous.
Students under the age of 18 shouldn't be exposed to adult entertainment because it's not right to corrupt children with the nasty things that adults call entertainment. That stuff should stay for adults only no children under the age of 18 it's wrong. It's like you're teaching the child that stuff and then the children would start to do it