When three persons go into a public-house, call for liquor generally considered sufficient for two, and have a glass which will divide it into three equal portions, they are said to "drink three outs."--James Halliwell's Dictionary of Archaic and Provincial Words, 1855
Feast Day of St. Adelemn,
a twelfth-century French patron of waiters and manservants. A more treacherous form of freeloading in pubs, known as "shooting the crow," was described in Albert Barrére's Dictionary of Slang, Jargon, and Cant (1889): "An ancient sinner was recently charged with 'shooting the crow' -- obtaining alcoholic stimulant at public-houses and making an artful retreat without paying for the cool, refreshing moisture. His method was charmingly simple. After strolling into a coffee-room, he would order a 'six' of whisky. On the liquor being brought, he usually remarked, 'The water in the bottle looks rather cloudy, waiter. Fetch some fresh, if you please.' Then, while the gentleman garçon retired, the [customer] invariably drank the spirit with rapidity, and made tracks as speedily as possible. Fifteen days hard [labor]."
So that's a "lower-case 'c' with cedilla," eh? Learn something new every day.