Is tongue piercing allowed?

So the general principle for any type of piercing is that it goes back to as long as something is not known as mutilating one's body. Now how do we know what is defined as mutilating one's body? There's no specific verse in the Quran, no specific Hadith as such, so it goes back to what is the custom of the people in that area as to what is considered to be part of the norm or not. So for example, ear piercings generally are part of the norm for females, and nose piercings for example as well. Now any other type of piercing: is it something which would be seen as something which is slightly out of the ordinary, something which is not the norm, which then may be considered to be part of mutilating one's body? If it is in that category, then yes it should be avoided.