These are people I have no interest in having a relationship with, so pretty much anything goes.

Example:

Them: I thought what Fred said earlier was really offensive. What did you think?

Me: I didn't really think much of it. Kind of stupid, but I wouldn't say I was offended.

Them: [Explains to me why I should be offended]

Me: (very uncomfortable) [Here is where I need something to shut them down and make them never try this with me again, or maybe stop talking to me entirely: I don't care.]

The best I can think of is, "I don't want you to... Try to persuade me to be offended..." (While looking at them like they just asked me to go streaking through Apple's corporate office with them).