A rogue or villain: a term borrowed from the chase; a rascal originally meaning a lean shabby deer, at the time of changing his horns, penis, &c. whence, in the vulgar acceptation, rascal is conceived to signify a man without genitals: the regular vulgar answer to this reproach, if uttered by a woman, is the offer of an ocular demonstration of the virility of the party so defamed. Some derive it from RASCAGLIONE, an Italian word signifying a man. without testicles, or an eunuch.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Raree Shew Men * RatNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes