Final answer:
The central idea in the selection from Bad Boy is that making fun of people in 'harmless' ways can have lasting negative effects.
Step-by-step explanation:
The central idea in the selection from Bad Boy is that making fun of people in 'harmless' ways can have lasting negative effects. The text discusses how categorizing people into in-groups and out-groups can lead to negative behavior and judgments. It emphasizes the importance of being aware of the sensitive nature of this topic when interacting with others to avoid alienation and negative consequences.