Kangxi is here. Manager Yin's good friend is Professor Lan. What is the punch line?

The sentence "Kangxi came to Yin's good friend is Professor Lan" is a joke in itself, because it has no practical significance. It produces humorous effects through meaningless language and absurd logic.

The beauty of this joke lies in the absurd connection between Kangxi, Manager Yin and Professor Lan. Kangxi was an emperor in the history of China, and Yin Guanzong and Professor Lan were two fictional characters from Taiwan Province Province. It is absurd logic and humorous to associate these three completely different characters and identities and describe Manager Yin's good friend as Professor Lan.