Two things come to mind about why someone would do what they did to that green machine:
1. Desert lizards bob up and down in displays of male aggression during mating season. They will do this if they are on the road and your much larger vehicle runs over the top of them turning them into road goo. So, maybe the car owner thinks this is a male aggressive thing to show off his manliness and testicular vigor. Just drive your Hummer over the top of his vehicle.
2. I once saw a movie (can't remember what it was called), but a motorcycle cop pulled this guy over. The cop swaggered over to the driver. He had his nifty motorcycle cop uniform on, the tight breeches, the black, shiny leather boots, the helmet with the CHP logo on it, and those shiny mirrored sunglasses that never come off because like a Stephen King novel, his real eyes are shiny mirrors. He eyes the driver, gives a scathing forward and back review of the driver's vehicle (some vehicle in the category of a Plymoth Duster or a Yugo), and says, contemptuously: "Ya know, even if you put a lot of money into this car and brought it up to cherry condition, you'll still have a piece of crap." Then he walked away leaving the driver to ponder this truth. So, maybe someone put a lot of money into his piece of crap.