Curley mistakenly thinks that Lennie is laughing at him with the other men, when, in fact, Lennie is not aware of the drama between Curley and Slim and is simply chuckling to himself with glee thinking about the dream farm. Curley, who has just been embarrassed in front of the workers, picks a fight with Lennie, thinking he'll earn some respect back by beating the much-larger Lennie. Lennie defends himself and attacks Curley only when George tells him to do so. In the scene, George says, "Get 'im, Lennie!" This moment feels very much like a master siccing his dog on someone. Lennie follows George's command and breaks nearly every bone in Curley's hand.
