How to get a tattoo in michigan without parent consent?

Hi well as the title says im wondering how its possible because i wanted to get a remembrance cross for my grandpa and my parents wont sign they said i would have to wait until im 18 and i already know now people are going to comment saying that you should wait and think well im saying i have thought hard about this for 2 years straight i drew up some designs on it and everything i know what im doing i just was hoping to get it before im 18 and i have a friend who got one and she is only 14 but i don't think she even got parent consent for it thanks for the help in advance its much appreciated