take down a peg
take someone down a peg (or two)and take someone down a notch (or two); knock someone down a peg (or two); knock someone down a notch (or two)
Fig. to reprimand someone who is acting too arrogant. The teacher's scolding took Bob down a notch or two. He was so rude that someone was bound to knock him down a peg or two.
take (someone) down a peg
To reduce the pride of; humble.