Breaking the news to my mother about getting a tattoo?

You are 21 years old, you are an adult..you don't need your parent's permission anymore. What's the worst they can do to you if they find out that you get one? they can't ground you anymore or take your computer, phone or game console away. They might be upset with you for a bit but they will get over it and respect your decision sooner or later if they love you.