打不赢的小怪兽

In Chinese pop culture context, especially influenced by Japanese anime culture, '小怪兽' (little monster) sometimes refers to a character from Ultraman series. '打不赢的小怪兽' implies that the person can't win against a little monster, depicting themselves in a funny or self-mocking way, suggesting they're not good at fighting games or simply cannot cope with challenges sometimes in life but remains endearing despite those flaws.