Image
© MSN
You probably don't think about what's under the street much, but you might start to now. A sinkhole opened up in the middle of a Philadelphia street, and it was apparently full of this green ... stuff. What does this mean? Are secret tunnels below the streets pumping radioactive goo across the country for some nefarious purpose? No. As the Redditor who took this photo learned, this is actually a fluorescent dye. Cities add it to water in sinkholes to see where they go, and hopefully fix the problem that causes it. Still, nearby pizza restaurants should be on the lookout for a pack of giant talking turtles. Just in case. [Source]