What does Winston wake up and mutter?
I assume you are talking about the passage in Chapter 3 where Winston wakes up from a dream and then starts to do calisthenics when ordered to do so by the woman on the screeen.
If so, the word that is "on his lips" when he wakes up is "Shakespeare."
In this passage, Orwell is trying to show that Winston is someone who thinks for himself and wants to be free from the tyranny of the state he lives in. This is symbolized by his dream of the girl. He doesn't care so much about the fact that she's naked -- what he cares about is how graceful and careless and free it looked when she took her clothes off.
The word "Shakespeare" sort of goes along with this because it symbolizes a part of humanity where people are free to dream and think and be creative.