Why is Li Randi called Dahe?

This is related to "Song of a Hero". Li Randi sang "Song of a Hero" whenever he had nothing to do, and it sounded like a ghost, so netizens called him Li Randi Dahe.

Li Randi asked fans to call her Li Dahe, like her family, friends and classmates. Li Randi said that the nickname came from a song "Heroes" during a class performance, and the nickname "Dahe" came from it, and Teacher Dahe happily accepted it.