Help convincing my mum in letting me dye my hair??? =)

Ok the low down...
My mum said i could have BLUE Streaks in my hair for this concert i'm going to in a few weeks which is okay. BUT i really want to dye all my hair black. All my friends said it would work (kinda got a Joan Jett hairstyle going on, but blonde doesn't work).
My mum is REALLY strict on this kinda thing. How can i ask her without her freaking out. And what is a good argument to win my case?