Yo coooooool
try certain brands of soap (no I'm not kidding the stuff you wash your hands with) some bars work real well and are great for drawing pictures on walls.
A loooooong time ago we did a room out in UV pens, we drew around all the edges of the furniture, the TV the stereo the pattern on the sofa, the door frames, the windows, the carpet, turn on the UV light and its like being in a scene from tron, it looked awesome.
Oh yeah many varieties of moths have UV reflective wings and they look cool as shit flying round the room when your having a smoke
