[? each drink was seen as a ‘peg [i.e. nail] in one’s coffin’; but note 17C SE peg, ‘one of a set of pins fixed at intervals in a drinking vessel as marks to measure the quantity which each drinker was to drink’ (OED)]
[early 19C+] (orig. Anglo-Ind.) a drink, esp. of brandy and soda.
[1920s–30s] a public house.
go a peg lower
[19C] to drink heavily.
[late 19C+] a champagne cocktail, champagne mixed with brandy.
put in the peg
(alsoput on the peg)
[late 19C–1920s] (Aus.)
1. to stop doing something, esp. to stop drinking.