(informal, chiefly African-American Vernacular) To clench one's fist(s) as though in preparation for a fight. / (informal, by extension) To approach a problem aggressively.

(slang, vulgar) Semen or ejaculate resulting from masturbation.

(informal) A credit card imprinter.

plural of knuckle-tat

Alternative spelling of moose knuckle

plural of moose-knuckle

An extremely exciting ride at an amusement park, etc., where one's hands grip on so tightly that the knuckles appear white. / (figuratively) Any extremely exciting or nerve-racking experience.

Alternative spelling of white-knuckle ride

(slang, vulgar) masturbation

The original form of boxing, in which no gloves were worn.