Peg too Low
(A). Low-spirited, moody. Our Saxon ancestors were accustomed to use peg-tankards, or tankards with a peg inserted at equal intervals, that when two or more drank from the same bowl, no one might exceed his fair proportion. We are told that St. Dunstan introduced the fashion to prevent brawling.
Come, old fellow, drink down to your peg! But do not drink any farther, I beg.
Trepanned your party with intrigue, And took your grandees down a peg.
There are always more round pegs than round holes. Always more candidates for office than places to dispose of.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894