妞爷的心你不懂
[niū yé de xīn nĭ bù dŏng]
This nickname conveys a message that 'you cannot understand the heart of this girl', expressing the speaker's belief in a certain depth or complexity to her inner world that others cannot easily fathom. Here, '妞爷' can be translated as a strong or unconventional girl and '心你不懂' translates into 'a heart you don't understand'.