Can you tell what it is? I don't want to give it away. Leave your guesses in the comments section.
I'll give you a hint: pay attention to the license plate in the context of the rest of the information on the truck.
The photographer swears this isn't Photoshopped and that this is exactly what she saw on her morning commute today. If you look at the hood of the car, the reflection "bears" this out (and that's a freebie for you).
And don't worry if you don't get it, you probably have to be an animal geek like me to a) get the joke and b) think it's funny.
Photo by Maria Meriwether.