There a European commercial I saw once: A little boy goes into the bathroom to stand up and pee in the toilet. The shot is framed from behind through the doorway so you can't see much. But you hear the pee hitting the water. Then, off camera, the mom calls out for the boy. He half turns to answer - the view still blocked by the door frame. But now we hear the pee hitting the floor. It is a commercial for a cleaner/disinfectant product, of course.