handmade dick noun a large or curved penis US An allusion to the belief that excessive masturbation will produce a larger-than-average or curved penis.
— Dale Gordon, TheDominionSexDictionary, p. 81, 1967
His dick was curved to the right, as if the use of his right hand had fixed the curve in it. Masturbation, or too much tender handling made it what men called a handmade dick. — Donald Goines, Swamp Man, p. 67, 1974