A bar-boy; also a bastard or any other child. To stifle the squeaker; to murder a bastard, or throw It into the necessary house.—Organ pipes are likewise called squeakers. The squeakers are meltable; the small pipes are silver. Cant.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Squeak * Squeeze CrabNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes