She screams.
"When Lennie explains that he likes to pet soft things, Curley's wife reveals that she too likes to feel silk and velvet, and she invites him to feel her hair, which is very soft. He does, but his big, clumsy fingers start to mess it up, and she angrily tells him to let go. As she tries to get her hair away from Lennie, he becomes scared and holds on more tightly. When she begins to scream, Lennie covers her mouth with his hand. A struggle ensues — Lennie panicking and Curley's wife's eyes "wild with terror" — until her body flops "like a fish" and then she is still."
