Tattoo...what to do to get bf letting me have one?

Okay, my boyfriend doesn't want me to get one. I understand why, but I still would like one... a very neat colorful (not to big) erfly on the back right shoulder. His last two girlfriends before me had "tramp stamps" of erflies and he's not too happy about myself having a erfly.. or any tat. But... They are like good luck charm to me and I had put this tattoo into a great deal of thought for many years... I respect my boyfriend and would not get one for him... but I still long for it. What should I do? Thanks!