bring/take somebody 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.
ˌbring/ˌtake somebody ˈdown a peg (or two)(informal) make somebody realize that they are not as good, important, etc. as they think they are: He didn’t win first prize after all. That’ll bring him down a peg or two. ♢ It’s time that somebody took that woman down a peg or two. She behaves as if she were the queen.
take (someone) down a peg
To reduce the pride of; humble.