How to Make Your Urine Glow in the Dark. A friend told me last night that if you boil urine and let it cool, it’ll glow in the dark. “Well, let's do it,” I exclaimed, to which he shook his head. Naturally I was immediately suspicious, like any budding scientist would be, and accused him of lying about the glowing urine trick, but he said it wasn't an appropriate activity for two friends to share.