我不是你的凹凸曼你却是我的小怪兽
[wŏ bù shì nĭ de āo tū màn nĭ què shì wŏ de xiăo guài shòu]
In Chinese culture, '凹凸曼' ('Aotuoman') comes from a popular cartoon superhero. This phrase humorously says: I am not your savior while you are actually my little monster or something difficult in life. But this expresses affection or helplessness towards a naughty yet precious thing/person in one's life.