Chopstick etiquette: never point at people with chopsticks, don't stick them upright in rice (resembles funeral incense), and don't pass food from chopstick to chopstick (a funeral ritual). Tapping your bowl with chopsticks is also considered rude.
history
The character 筷 has the bamboo radical (竹) on top because chopsticks were traditionally made of bamboo. The word was originally 箸 (zhù), but because it sounds like 住 (to stop), superstitious boatmen renamed it 快 (fast/lucky), later written as 筷.
