From Longman Dictionary of Contemporary Englishwhippersnapperwhip‧per‧snap‧per /ˈwɪpəˌsnæpə $ ˈwɪpərˌsnæpər/ noun [countable] old-fashionedSSYRUDE/IMPOLITE a young person who is too confident and does not show enough respect to older people
Examples from the Corpus
whippersnapper• An older Tony Gwynn must compete only with that whippersnapper and a young Dave Winfield with an aversion to the right-field wall.Origin whippersnapper (1600-1700) Probably from snipper-snapper “whippersnapper” ((16-19 centuries)), probably from snip + snap 