When someone mocks a teacher behind their back, you don’t have to join the choir.

Group mockery runs on momentum. Every new voice makes the next one easier and makes silence feel like a statement, which it usually is not. You do not have to defend anyone or make a speech in order to step out of it. Neutral is a real position, and most of the room will not even register that you took it.

Say nothing, or ask one flat question that adds no fuel. If the group is being genuinely unfair, a single sentence halves the momentum. Then let the conversation drift somewhere else, which it always does.