1984 Book 3, Chapter 5 Summary

O’Brien tells Winston that the worst thing in the world is in Room 101. What is the worst thing in the world, you ask? Well, it depends on the person.
For Winston, that thing is rats, in an Indiana Jones and snakes kind of way.
O’Brien threatens Winston by showing him a cage of large, vociferous rats, waiting to gnaw away at Winston’s face.
Winston, with the rats just inches away from his face, is terrified. The oh-so-chivalrous Winston shouts out, "do it to Julia!"
That does the trick for O’Brien. He’s satisfied. No more private loyalty = only party loyalty to Big Brother.