Room 101

"For a moment he was alone, then the door opened and O'Brien came in.
'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.'
.......
'The worst thing in the world varies from individual to individual. It may be burial alive or death by fire, or by drowning, or by impalement, or fifty other deaths. There are cases where it is some quite trivial thing, not even fatal.'"

From:
Nineteen eighty-four
George Orwell (pseudonym of Eric Blair) (1903-1950)