Step-by-step explanation:
In Chapter 5 of "Of Mice and Men," Lennie is in the barn alone, petting his puppy, when he accidentally kills it by petting it too hard. When he realizes what he has done, he becomes panicked and afraid of what George will say and do when he finds out. Lennie's fear and panic lead him to try to hide the dead puppy in the hay.
As a result of his panic, Lennie's mental state becomes increasingly unstable, and he begins to hallucinate. He sees a vision of his Aunt Clara scolding him for his behavior and telling him that he will never get to tend the rabbits on their dream farm. Lennie becomes agitated and upset, and he begins to cry out for George.
This event is similar to an earlier one in the story where Lennie becomes scared and panics after accidentally killing Curley's wife. In both instances, Lennie's lack of understanding of his own strength and the consequences of his actions lead to tragic results. His fear and panic also cause him to act irrationally, leading to further problems.