How do I convince my parents to let me go to Bamboozle?

I'm 14 (but I look 17, tall and somewhat muscular). This girl I really like is going and invited me to come with her, and I don't know what to say to parents to let me go. I've been to concerts where there was moshing/druggies etc, and I know I can handle this. How can I convey that to my folks?