妲己不倾城
[dá jĭ bù qīng chéng]
This internet username refers to 'Daji', a historical figure from ancient Chinese mythology who is famous for her beauty that could topple a nation. However, the addition of 'not倾城' suggests that this Daji does not cause cities to bow down or be destroyed, indicating a softer, less devastating beauty. A humorous self-deprecation by a beautiful girl.