threepenny-worth of whisky and water; thus generic for any quantity of whisky.
|‘’Arry on [...] the Glorious Twelfth’ in Punch 30 Aug. 97/2: Them Moors is the spots for cold Irish, and gives you the primest of pecks.|
|Minor Dialogues 205: Will you kindly gi’ me ’n Irish cold.|
|Passing Eng. of the Victorian Era 129/1: Fenian (Peoples’, 1882 on). Three cold Irish, i.e., threepence worth of Irish whisky and cold water.|