Why is tofu, among all foods that can be enjoyed hot, used in the expression "心急吃不了热豆腐"? Why not "心急吃不了热饭" or "心急吃不了热牛肉"？
After tofu is made ready to eat, it is very hot. And even the outer part of the tofu get cooled down, the inner part is still very hot. It someone tries to eat it in a hurry, he will be hurt by the high temperature inside.
Rice or beef or some others cannot keep the inner part at a high temperature while the outer part is cooled down.
PS. When you try to eat tofu, please be careful.
PS2. sorry for the English, feel free to correct me.