How to get your parents to let you get a lip piercing?

im 12 gunna b 13 in november nd i rlllly want snake bites or spider bites for a long time my mom said she wil think about it wen im 15 (so probably no) nd my dad says no nd ineed a way to make them say yes i was going to let my friend do it at a sleep over but my mom found out nd plz dnt say sumthing to try to shange my mind or say im to young bc i wnt change my mind