For hundreds of years Newgate would have made Abu Ghraib seem like Disneyland. Tales of its horrors are legion. In its day hangings were saved for public holidays and although intended by the city's fathers to be a warning to wrongdoers, in fact turned into something like the Notting Hill Carnival. It is said that 200,000 citizens, half the city's population, turned out to see their hero Jack Shepherd finally get his comeuppance. (The bounty hunter who turned him never got chance to enjoy his reward, meeting his own end at the hands of Jack's many friends.)
The 'Drop' and the broken neck it caused was a later mercy granted to the condemned to finish them off quickly. In those days, hanging was a slow and intentionally tortuous affair of slow suffocation. Death could only be hastened by human intervention - by paid members of the crowd or by determined family and friends who would rush forward to pull on the hanged person's legs.
Dickens was one of those so appalled by such sights that he became instrumental in them being carried out in private behind the walls of the prison and eventually stopped altogether. But not before they had cause to pass into the phraseology and slang of the English language. So, if you know any celebrities, you could remind them of the origins of their words, when they complain about 'hangers on'..
But be warned, they may think you are just 'pulling their leg'.