How can I convince my mom to let me pierce my lip?

My mom is very strict when it comes to piercings. I just got my earlobes about a month ago & that was my first. I'm 15 years old & I really want my side labret done. All my friends parents let them get piercings but not mine. & whenever I say " oh my friend has hers! " my mom will say " well I guess her mom loves her more. " as a joke. She says I'm too young to make that decision but I can always take it out if I get sick of it. I've been thinking about it for a while & it's something I really want.