Johnny kills bob

• • The scene episode in S.E. Hinton's book "The Outsiders," where Johnny murders Bob, represents a dramatic shift in both the plot and the lives of the characters. Johnny made the decision to carry a switchblade as a direct result of a past horrific event in which he was severely physically and psychologically damaged after being viciously attacked and beaten by a bunch of Socs. He was scared after this and felt compelled to defend himself at all costs.   
• When Ponyboy and Johnny, members of the less fortunate Greasers gang, are insulted by the Socs, a band of affluent and privileged youths, the argument in the parking lot quickly gets out of hand. For a considerable amount of time, the two groups have been under conflict due to their disparate social backgrounds and shared contempt. The Socs' disparaging comments about the Greasers, referring to them as "white trash with long hair," cause the Greasers to sharply respond, mocking the Socs as "white trash with mustangs and madras," emphasising the  difference between them
• "We can't win" - Dally (Dally) acknowledges that they will always be seen as inferior compared to the socs because of their economic status.
• When Bob, one of the Socs, tries to drown Ponyboy in a fountain, things become really bad. Johnny responds to the impending (approaching) danger to his friend's life in the only way he feels capable of—by stabbing Bob with a switchblade. His actions are motivated by both pure terror and the need to survive. Even though Johnny and Ponyboy are acting in self-defense, this violent act starts a series of circumstances that drive them to leave their hometown after they realise staying there could result in their arrest and even imprisonment.
• Johnny's admission, "I killed him," underscores the gravity of the situation and his awareness of the consequences of his actions, even though they were driven by the need to protect himself and Ponyboy. 
• This incident serves as the story's catalyst, sending the two boys on a terrifying adventure that puts their morality, friendship, and loyalty to the test. Additionally, it draws attention to the novel's larger themes, which include the consequences of social divisions, the need for identity, and redemption in an often unfair and unforgiving world.