How do I ask my mom to shave my legs?

I'm almost 13 and i have dark leg hair. All my friends have been shaving for a year or two now. It's starting to be summer and I will not wear shorts in public. I am really nervous about asking my mom. She did ask me 2 years ago, I said no because you couldn't even see my leg hair and i didn't mind it. But she hasn't asked me since! Now i actually have leg hair! during basketball season i even wore high socks so now one could see my leg hair. And like i said i only wear long pants in public. Hello mom get a clue. But anyway i have no courage in talking to my mom about that subject. Im not going to just do it because when she sees im sure she will get mad. And i cant leave her a note or something because my brother( who on more than 1 occasion has told me to go shave) would find it. I can't email her because her email can be accessed by anyone in my family. HELP! Please soon as possible i do not want to wear sweats in 90 degrees or wear shorts cause my cousins who are younger than me already shave.