她姓牛我心牛他姓张我心脏
[tā xìng niú wŏ xīn niú tā xìng zhāng wŏ xīn zàng]
This nickname reflects a play on words where 'niu' sounds like the surname 牛 (meaning ‘Ox’) but also means 'awesome/great'. The user's love interest is surnamed Zhang (张) who evokes an intense emotional reaction from the user.