I think I should be allowed to chat online with the girls after school
Is there a reason that you would not be allowed to chat with the girls?
I know for a fact I will get in trouble if I do it
If it would get you in trouble then it must be against the rules. It is best that you not do things that will get you in trouble.
But what if the rules are unreasonable and onerous?
Then I think you might have a case. Just submit your protest respectfully.