So how would you resolve this issue if you have a stubborn mother and an obeying sister? I don't see how breaking one of the Ten Commandments would come into play with a cartoon show such as Adventure Time. Adventure Time likes to break away the viewers from the norms and show them the abnormality. To be honest, Adventure Time should not be for younger audiences as there are jokes there that are meant for a more mature audience. But your sister is 11, she probably knows what hidden contexts and meaning are in the show, so she should have a right to watch it.
Just give it some time to cool off in your home, as of right now it's a war zone against Adventure Time. Your mom would probably realize that she was over reacting on the situation and allow your sister to watch it again.
FateModified
Parents not letting their children watch "Adventure Time!?" What is this world coming to? What's next, parents forbidding their children to watch SpongeBob Square Pants? That would be an injustice against all humanity!!! For the love of cheese and rice, parents, please stop all of the madness before it is too late!!!
megadrivesonic
You seem to miss the point of this journal, I wrote this because the reasons were quite moronic on their part.