What do you think about me telling my wife that she cannot get a tattoo?
Is there a reason why you don't want your wife to get a tattoo?
Well, she is the one who wants to tattoo herself.
Getting a tattoo is a personal choice and while you can make your opinion about tattoos known to your wife, it isn't acceptable for you to give an ultimatum and prevent your wife from getting one. Your wife's body is her own and it's wrong of you to try to exert control over it. If your wife is set on getting a tattoo, you should try to compromise with your wife and decide on a design that both of you would find aesthetically pleasing.
This is getting way out of the world. I'm reconsidering the whole marriage thing.
I understand your concern about your wife wanting to do her own tattoo. However, you shouldn't tell your wife what she can do with her body. If she feels this is a skill that she wants to develop, all you should do is be supportive.