我是个乖孩子
[wŏ shì gè guāi hái zi]
Translated simply as 'I Am a Good Child/Boy/Girl,' this expresses adherence to good manners and behavior. This kind of screen name can imply a preference for being well-behaved or conforming to social expectations, but sometimes also humorously self-contradictory in casual online interactions where users express a different side of themselves.