whippersnapper
noun[C]
old-fashionedorhumorousuk/ˈwɪp.əˌsnæp.ər/us/ˈwɪp.ɚˌsnæp.ɚ/ayoungpersonwho is tooconfidentandshowsnorespecttowards other,especiallyolder,people:
妄自尊大的年轻人，自命不凡的年轻人I'm not going to have someyoungwhippersnappertellme what to do!我可不需要什么不知天高地厚的年轻人来告诉我应该做什么！