Optic Topic (Luminescence) : Blacklight tattoo.
Blacklight tattoos are normally invisible under white light but glow fantastically in the dark because of a special ink used in them. They are more expensive and very little research has been done into the side-effects they might cause. It covers all your "please can I see my tattoo 24 hours a day, at anytime I want too" needs while perhaps also getting sick from it. Perfect!