Red bull (feminine: red cow)[a] is a pejorative label from Vietnamese social media used to describe Vietnamese public opinion commentator.
[1][2] Red bulls not only support Vietnamese government unreasonably but also monitor active Internet users and harass or scare dissidents.
[1][4] The slang was inspired by the South Vietnam flag and its yellow background.
Sometimes, people who do not criticize the Vietnamese government or praise state-made films such as Đào, phở và piano [vi] are labeled unfairly as red bulls.
[4][5] According to PhD Nguyễn Phương Mai, this is an indication of political polarization.