Right speech in social situations

My boss has a tendency to gossip and speak negatively about his clients when they are not present. Sometimes he speaks to me about these people, and I am unsure of how to respond with regard to right speech. To not respond at all may hurt his feelings and create friction in our workplace. But to engage in such a discussion about others surely is wrong speech. How should one go about responding to gossip while maintaining right speech *and* prevent hurt feelings/social awkwardness?