世界上只有我可以欺负你世界上只有你可以欺负我
[shì jiè shàng zhĭ yŏu wŏ kĕ yĭ qī fù nĭ shì jiè shàng zhĭ yŏu nĭ kĕ yĭ qī fù wŏ]
Translated as 'In this world, only I can tease/hurt you, and only you can do that to me.', this implies an exclusive, deeply close relationship between two people, perhaps partners who playfully or affectionately joke around but also trust each other implicitly.