她的奥特曼我的小怪兽
[tā de ào tè màn wŏ de xiăo guài shòu]
'Her Ultraman my monster' refers to a couple using popular Japanese culture as analogy: Ultraman is a hero who fights against monsters, and the user may be indicating in a playful way how the other party acts like a superhero while they play the part of the creature to each other.