In the Japanese culture, not only is it rude to stick chopsticks upright in your food, its also bad luck when you go for the same piece of food or clash chopsticks. You are also not supposed to pass food chopstick to chopstick, if someone offers you food, youre supposed to receive it with your bowl, not your chopsticks.
The informant was born in Kanagawa, Japan, a bay area close to Tokyo. He grew up in Hawaii but still retains much of Japanese culture and traditions. As a child, the informant was berated by his parents when he played with his chopsticks at the dinner table. His parents told him that passing food and clashing chopsticks resemble what people did at funerals. In most Asian cultures, the dead gets cremated. After the body turns into ash, close relatives all pick out the bones with their chopsticks and pass them down until the bones get put in a special jar. When offering food to the dead, one would purposely put chopsticks upright in the rice so the spirit can come back and eat the food with given chopsticks. Thus, it is very disrespectful and looked upon as being bad luck when one places chopsticks in any of the aforementioned manners at a dinner table.
Since hearing these stories, the informant grew up respecting these traditions. He thinks these traditions are there for a reason and that when people mess around with chopsticks at a table, theyre defacing something sacred and disrespecting the dead as well as the dinner hosts.
I think this is interesting because all Asian cultures, Chinese, Japanese and Korean all have these chopstick rules. While I know youre not supposed to pass down food chopstick to chopstick or clash with someone, I never knew the reasons why. It also speaks a lot about these cultures historically and geographically. It shouldnt be just a coincidence that they all have the same traditions and superstitions.