In order to welcome the Jade Emperor and show him the poverty and hardship of human life, people are cautious in their words and deeds and leave a good impression on the Jade Emperor with their good performances.
In addition, we have to make tofu and eat the bean curd residue filtered out when making tofu to show that we are poor and frugal in life. This is as the saying goes, "On the 25th of the twelfth lunar month, eating tofu residue is a poor way to welcome the Jade Emperor".