Dukes

etymonline

ref

dukes (n.)

"hands," 1874, now mainly in put up your dukes (phrase from 1859), probably not connected to duke (n.). Chapman ["Dictionary of American Slang"] suggests Romany dook "the hand as read in palmistry, one's fate;" but Partridge ["Slang To-day and Yesterday"] gives it a plausible, if elaborate, etymology as a contraction of Duke of Yorks, rhyming slang for forks, a Cockney term for "fingers," thus, by extension, "hands."