Final answer:
The phrase "I said, so what?" is dismissive, often used to silence someone or show dominance in a conversation, resulting in the other party being unable to respond.
Step-by-step explanation:
The phrase "I said, so what?" generally indicates a dismissal or lack of concern for the previous statement. In the context of "that shut her up like a clam," it implies a reaction that silences someone, likely because the phrase is confrontational or dismissive enough to end the conversation or leave the other party without a response.
This interaction suggests a change in the dynamics where one party establishes dominance or ends the discussion decisively.