In the film, Shan Rui calls the hero Guo Guo, which means brother. Finally, Shanrui shot and killed the bad father. However, Shanghainese can't tell three from mountains, so "three Rui" has gradually become a special word for Shanghainese to scold others for mental retardation. The enhanced version is Sanrui Guoguo.
Extended data:
"Tianya Children Singing Birds" is a TV series about a group of people. Shanrui is a fool. He called "brother" Guoguo. Because this film has a great influence, all "Shanrui" has become synonymous with "fool" and so on.
Three idioms describing people's stupidity include ignorance, stupidity, stupidity, stupidity and stubbornness.