My sister was about the same age, I think 18 or 19 though, and had the same desire. She finally got it, a little flower on her ankle, and my parents didnt want her to get one either until she moved out. When they saw it they were a little upset but came around eventually.
I think the size has alot to do with it too and what it is. So just be careful cuz remember its going to be with you forever.
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