Why do people in Suzhou call themselves eating tofu after they die?

It means longevity.

Eating tofu rice is a folk funeral custom popular in Jiangsu, Zhejiang and Shanghai.

After the funeral, the locals hold a banquet, commonly known as the Bean Banquet, to reward the relatives and friends who came to attend the funeral and the neighbors who helped.

The person being invited will generally not refuse, otherwise it will be considered rude.

The ancients believed that the cause of the deceased's death was either disease or misfortune, and that the aura of plague would inevitably surround the body. Therefore, mourners were asked to eat soy foods to remove the aura of plague or ominousness.