John Ketch, generally known as Jack Ketch, (died November 1686) was an infamous English executioner employed by King Charles II. He became famous through the way he performed his duties during the tumults of the 1680s, when he was often mentioned in broadsheet accounts that circulated throughout the Kingdom of England. He is thought to have been a...
The hangman. To dance with Jack Ketch is to hang.
• A public executioner, or hangman.
Jack' Ketch' [ Perh. from Jack , the proper name + Prov. E. ketch a hangman, from ketch , for catch to seize; but see the citations below.] A public executioner, or hangman. [ Eng.] « The manor of Tyburn was formerly held by Richard Jaquett , where felons for a long time were executed;...
Jack Ketch is London Cockney rhyming slang for a prison sentence (stretch).
The hangman. To dance with Jack Ketch is to hang. 
The hangman. ?Dance with Jack Ketch? means to hang