How can i convince my parents to let me get my bellyon pierced?

Okay , I turned 14 in November + I reeaalllyy want to get my belly on pierced. Its not because "everyone" has it , because only two people i know my age do. People are talking about getting it done soon though. First of all, if i am going to get it done , i want to get it before those people do, so its not like im copying or anything.The one part of myself im actually confident about is my belly, - i have the perfect stomach for it, and i lovee the way bellyon piercings look. My mom actually agreed, but then she changed my mind when my dad said no, and of course - denied she had ever agreed. Whenever i mention it, my dadjust says it looks slutty, trashy, etc. . . . he just keeps thinking up synonyms for the same words and wont elaborate more ! I really just want it done because i like the way it looks. I am going on a cruise at the end of march, so i want it done before then, soon so it has some time to heal. How can i convince them(mostly dad) to let me get it done?!