Tongue Tattoo

Tongue tattoos are possible. The pigment won't hold.
In the 1820's the Hawaiian Queen Kamamalu received a tongue tattoo to show her grief after her mother in law's death. This was witnessed by a missionary named William Ellis who commented that the queen must be in great pain, she replied; "He eha nui no, he nui roa ra ku‘u aroha." (Great pain indeed, greater is my affection.)