What are best weapons against midgets and really obese children?

Like if I get cornered in an alley with my sickly grandmother whom I’ve taken out to the park because I’m a good grandson. And we are both ambushed by midgets and morbidly obese children. Reason why we were in an alley is because we use it as a shortcut route to the local park in our town. In this scenario these hooligans are frequent bath salt users and have full unaware intentions to murder and rape us, due to the influence and effects of the bath salts. What is the best defense if I can not own a gun because I’m underaged and cannot acquire a CCL permit. In a perfect world I would have a Katana and a mini gun that I would carry in public and my fellow citizens would not be disturbed because it would be considered a sociatal norm. Again if only we lived in a perfect world. Any advice? What weapons, tactics, or plan should I have in case if I were in such an ordeal