The final words spoken by Wille,
Is bad. Is all bad in here now
are good indicators of how the atmosphere that permeated the friendship of Willie, Sam, and Happy has become damaged to the point of no return.
MASTER HAROLD...and the boys dramatizes Fugard's childhood in Apartheid South Africa, and an incident which destroyed a friendship forever. In the play, 17 year-old Hally's (who really represents Fugard, himself) loses control when he realizes that his father, a loser and an alcoholic, is about to return from a hospital stay for good.
Prior to this climactic event, we witness how Hally develops a father-son bond with a black server at the tea room that is owned by Hally's parents. This occurs because Sam, the server, is the only "normal" male role model that Hally has ever met. Along with Sam, Hally also befriends Willie, the other black server, who provides a comic relief to an otherwise charged atmosphere of racial tension and the problematic idea of a white and a black man being friends.
However, the moment that changes everything occurs when, at the possibility of Hally's father's return, Hally becomes anxious enough to call both Sam and Willie racial slurs, to treat them badly and then, to make matters even worse, to perform the ultimate insult that one person could give another: Hally spits on Sam's face.
When Sam, almost automatically, feels the urge to hit Hally, Willie stops him. When Sam takes every ounce of himself to become composed he gracefully extend his hand in hopes of erasing the incident and maintaining the friendship with Hally. Hally, however, is seventeen, immature and, most of all, he is deeply ashamed. So ashamed, in fact, that he refuses the peace offering and walks away embarrased.
The problem with this situation is the historical context of the play. This is also the reason why an action of this kind would mean something completely different in another time and moment.
Apartheid did more than merely separate blacks from whites; it was a movement that hurt the psyche of a race and made a major dent in the dignity of black South Africans. It was the ultimate act of human backwards behavior in that it retarded social change, rather than encourage it.
The atmosphere of tension and animosity was rampant and anything that was said or done would have been under deep scrutiny. For this reason, what Hally does in the play can no longer be read as a mere rebellious act; he literally shakes the very weak social foundation that could only be balanced by their mutual respect.
For this reason, Sam begins to show up late to work and he ends up getting fired. Like Hally's mother says
His work went to hell. He didn't seem to care no more
Therefore, it is safe to say that the incident left quite a negative mark in Sam for him to not care anymore. He loses his hopes and he is incredibly heartbroken by what Hally does. So much sadness this produced in author Althol Fugard's own life that he basically wrote MASTER HAROLD...and the boys as a way to somehow render homage to the kindness of his only true friend from childhood, Sam.