In 1984, O'Brien expects Winston to know what Room 101 is.
I know that Room 101 is more torture, but why would O'Brien expect Winston to know that?
‘What is in Room 101?’
The expression on O’Brien’s face did not change. He answered drily: ‘You know what is in Room 101, Winston. Everyone knows what is in Room 101.’
"You asked me once," said O'Brien, "what was in Room 101. I told you that you knew the answer already. Everyone knows it. The thing that is in Room 101 is the worst thing in the world."