It’s amazing what you can learn from reading comments. This picture was taken in Baton Rouge, Louisiana during the flooding of August 2016. There are a few car enthusiasts living in the area. The guy who played the Scooby-Doo voice, Scott Ennis, lives there, and the van was something that was done for a charity. I’ve never watched Supernatural, but I got the joke from this comment: I just imagined Sam and Dean AND Scooby and Shaggy looking at each other and going WTF!