whippersnapper

US /ˈwɪp.ɚˌsnæp.ɚ/

UK /ˈwɪp.ɚˌsnæp.ɚ/

kẻ ăn trộm

a young person who is too confident and shows no respect toward other, especially older, people:

•

I'm not going to have some young whippersnapper tell me what to do!