A rare instance of a phrase entering the English language and having a meaning quite distinct from any other English phrase - Room 101.
Nobody who has read and understood 1984 can fail to feel a tingle in the spine at the thought of Room 101. It is where people's minds are so totally destroyed that it creates the equivalent to complete re-programming.
Orwell demonstrates the necessity of using Room 101 by the amount of time Winston & Julia are allowed to continue their affair. Mr Cherrington, as a member of the Thought Police, was aware of Winston's unorthodoxy right from the start, so why was he allowed to remain at large? The Thought Police needed to be assured that they knew his deepest, most secret, most feared phobia. Many people have lots of fears - spiders, heights, the dark - but there will be one overwhelming fear which cannot be faced under any circumstances, and it is imperative for the Party to find out what it is.
Winston's rat episode is the trigger for action by the Thought Police.
With this fear exposed and exploited, O'Brien is able to destroy Winston's will - he is an empty vessel, signified by the change in attitude after he renounces Julia. The knowledge that he would swap places with the one person in the world he thought he loved more than himself is inescapable and Winston is able to be programmed like a blank disk.
When a prisoner is ordered to Room 101, he begins to scream and beg not to be taken there. Given that nobody who hasn't been re-programmed already knows what Room 101 actually is, I'm sure this man is a plant to allow the fear to fester in Winston's mind. He will be expecting the worst, then has the realisation that Room 101 is far worse than he could have imagined.
The question of what Julia's Room 101 might be has come up often.
The only clue - if it is one - in the book is Julia's loathing of the thought of sex with Inner Party members and I think there's a case that her Room 101 would have been multiple rape by Inner Party members.
Room 101 is the ultimate weapon in the world of the Thought Police. Only through its use can dissent be re-created as love - of both BB and the Party.
So, what was Orwell trying to say with Room 101?
He was teaching us that all things are possible within a mind if it is forced to confront its worst fear, that we all have those fears, and maybe, in his own way, George Orwell was trying to tell us not to let those fears overcome us - if we deal with fears, they will never grow to Room 101 proportions.
All continuing comments and questions are welcome.