In many rural families, when someone dies, they hold a white banquet, get a bowl of rice when they give it away, and then put three chopsticks upside down on the rice. Represents the consciousness of sacrifice, the living can't eat, basically someone died here, and that's what they do. There is also a saying that it was short hair in ancient times. There is also the time to put incense in the rice before offering sacrifices to the Buddha.
Not only this kind of consciousness, but also disrespect and impoliteness. In many places, this practice is only done when the messenger is perfumed, which is tantamount to perfuming the dead, so it is not only disrespectful to people, but also a manifestation of a person's lack of literacy. I think this is also a custom that we inherited from our ancestors. Every time you use chopsticks, there are different customs. Putting chopsticks in rice is a respect for the dead, not for the living. This is probably a common phenomenon in all parts of China. Of course, this is also very worthy of our deep thinking. This is just one of the taboos in the use of chopsticks. There are many taboos, as you know, such as not pointing at others with chopsticks when eating, and not knocking on the bowl with chopsticks when eating. Everyone has their own habits and choices, just respect each other, but you must know these taboos.