The reasons why Su Yongkang is called uncle are:

1. Su Yongkang is a Hong Kong pop singer in the 1980s. Uncle means uncle. Generally, people who are familiar with him will call him Uncle.

2. Su Yongkang's stage name is "Su Yongkang", which is taken from the idiom "never-ending, longevity and health", while Uncle is taken from the word "kang", which means health, so he is called Uncle.