too big for one's breeches

Adjective (1)

1. (used colloquially) overly conceited or arrogant“a snotty little scion of a degenerate family — Laurent Le Sage”“they're snobs — stuck-up and uppity and persnickety”Synonyms: bigheadedpersnicketysnootysnot-nosedsnottystuck-upuppishOpposite humbleSimilar proud