Lu Yu was a learned man of integrity who served as a senior official in the period of Three Kingdoms (220-280).
Once, the emperor of Wei was trying to fill a government post, and was studying a list of famous names put forward by his officials. The emperor said, "I want Lu Yu to select the right person, rather than choosing one of the well-known but useless individuals on this list. Fame is just like a pancake drawn on the wall. You cannot eat it."
Lu Yu suggested the emperor conduct examinations to find the best candidate. From that time on, officials were appointed according to their real ability and Lu Yu's method of selection was widely praised.
At first the idiom meant unjustified fame, but it later came to mean satisfying oneself by imagining things, or consoling oneself with false hopes.
huà bǐng chōng jī