This seems to be a very midwestern thing to do because we've not witnessed it on with coast we've lived in.
Enter fast food place (with ample seating, mind you), order and pick up food, exit building, turn on car, and eat food IN THE CAR while it idles in the parking lot.
They don't even drive anywhere. They just sit in the parking lot, in some instances staring INTO the place they got the food, and eating their food. Then, at some point later, they drive away.
Now why is that?!
** Editor's Note: I'm doing my best to make this about the behavior of eating in the car and not my personal repulsion of most fast food chains. It's not about the crap they are eating but the way they are consuming the crap.