How to convince my parents to let me get my septum pierced?

All these people saying "It's gross" "Don't do it" That's YOUR opinion. I doubt she cares what you think. If she wants it she can get it. Annnd to answer your question - why don't you tell your mom what you told us? If you explain all that then they might get persuaded. Maybe wait until you have enough money to pay for it yourself and use that to persuade them too. Do chores and help around the house. Btw, I think septum's are hot and if you want it you should go for it. (: And if you don't like it and take it out the scar won't even be visible. You win either way. :p