The youth group here did a glow in the dark sports night with necklaces in green and yellow for teams on Tuesday. I ended up with some of them after the evening and the kids went nuts! I've kept them in the freezer and they are still glowing. The only space in the house without windows is the downstairs bathroom so we went in and closed the door and it was magic!
Here is a picture with and without the flash for our "leftover" fun!