The characters combine to create a vivid and damning image: “to play with and neglect the duties you are meant to guard.” This structure emphasizes not just a passive failure but an active, almost contemptuous, disregard for one's responsibilities.
The term 玩忽职守 is deeply rooted in China's societal emphasis on duty, responsibility, and accountability, particularly for those in positions of authority. In a culture historically influenced by Confucianism, where every individual has a defined role and set of obligations, failing to fulfill one's duty is seen as a serious moral and social transgression.
This is a formal and serious term. You will almost never hear it in casual, everyday conversation among friends.