How to convince my mom to let me get a nose stud?

So i wanted one for like a long time. and every time i ask she ends up yelling at me. and she says no ure sister does not have one cuz she knows it will make me upset. or no cuz that leads to drugs or tattoos and i say no . and i also tell her that she does not let me be who i am and she said yes she does then i say then let me get one she says no. So i told my sister to take me and she snitched on me and my mom got pissed and i tell my mom i could just pierce it myself and she says don't be telling me that. but i just want one so some one plz help me!!!!!!!