Informant is my friend that has grown up in Taiwan and Canada, while also studying in LA.
Never, ever, ever put your chopsticks vertically into a bowl of rice. This is a physical resemblance to burning incense. We only burn incense when you go to a temple and usually during a funeral, so putting your chopsticks vertically into a bowl of rice is like praying for someone’s death. Not tot the point of like a threat or anything but like a sign of disrespect.
My mom has always told me as a child to never do this. I never knew the reason, but only knew it was bad. This has really given me some interesting insight into my own culture and why we do these things.