我贱我不知道我家里人知道
[wŏ jiàn wŏ bù zhī dào wŏ jiā lĭ rén zhī dào]
This nickname humorously conveys self-mockery and a possible hint of rebelliousness ('I am rude but only my family knows about it'). The term used here is informal and contains some humor, potentially even irony.