How to persuade my parents to let me stretch my ears?

What are some ways to convince my mother and dad to allow me to begin stretching? My mom's super religious and was pondering allowing me to get a second lobe piercing (she has 3 but the latest 2 she got in college) and my dad just thinks everything I do/wear makes me look like a slut (honestly, even capri pants make me look like one according to him xD.) I'm a relatively good kid; this year as a freshman I ended the year with a 3.9 and the semester with a 4.5 GPA. But in 7th grade I did a no-no and had someone at school pierce my helix, needless to say my parents found out a couple months later and they asked me if I wanted the other one done so it'd look even and I declined. Bottom line:I lost integrity points because of piercings in the past. Anyway, I've really studied up on stretching online and have asked around to friends that've stretched for advice. I've even considered the social stigma it'd carry and decided if someone can't accept me because of how big my piercings are, then I don't want to be ociated with them anyway. So how can I persuade my parents to allow me to stretch my ears? I really would like to stretch to a 0g or 00g. All advice is appreciated! Thanks!