Like Lord Thomond’s cocks, all on one side. Lord Thomond’s cock-feeder, an Irishman, being entrusted with some cocks which were matched for a considerable sum, the night before the battle shut them all together in one room, concluding that as they were all on the same side, they would not disagree: the consequence was, they were most of them either killed or lamed before the morning.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Thirteener * ThomasNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes