Just a story I like to tell...
When I was in college, I worked with the police as my internship project. 99% of it was riding along with the officers on duty. One time, we were sitting at a red light behind a car with three young ladies in it. The one in the backseat opened her window, turned and looked right at us, and dropped a crumpled fast food bag out. The officer that I was with said, "Did she really throw trash out the window right in front of me?" Without waiting for an answer, he shifted the cruiser to park, got out, went up to the car, picked up the trash, and put it back into the car, smiling and telling the girl, "You dropped something." He was chuckling as he returned to the cruiser and said that she looked surprised and scared that he did that.
Of course, she probably threw it out again once they'd driven away and there were no cops around...