Also,
take down a peg. Deflate or humble someone, as in
He's so arrogant that I wish someone would take him down a notch, or
That defeat took them down a peg. Both
notch and
peg in this idiom allude to a series, the former of indentations, the latter of knobs, used to raise or lower something. Specifically,
peg alludes to the pegs used to lower a ship's colors. Their figurative use dates from the second half of the 1600s. Also see
cut down, def. 4.