too big for your boots
自命不凡，傲慢自大
口语·批评自大
英文释义
to have an exaggerated sense of one's own importance or abilities
例句
Ever since he got that promotion, he's been too big for his boots.
典故来源
源自19世纪英国，比喻一个人自视过高，连靴子都装不下他的傲慢。