Source : WordNet®

too big for one's breeches
     adj : used colloquially of one who is overly conceited or
           arrogant; "a snotty little scion of a degenerate
           family"-Laurent Le Sage; "they're snobs--stuck-up and
           uppity and persnickety" [syn: {bigheaded}, {persnickety},
            {snooty}, {snot-nosed}, {snotty}, {stuck-up}, {uppish}]