This brings back memories of going to Target with friends and deliberately trying to get people like that riled up without even talking to them or directly interacting with them. They always will evesdrop on your conversations if they think you don't belong, so you can just talk about stuff you think they would disapprove of and get them so pissed off.

My favorite was to make fun of people who drive fake suvs. And to find a way to mention that I'm gay/bi in passing. If we succeeded, you could hear them angrily storm off from an aisle over. They would always stay an aisle away following us once they locked onto us, thinking they were being sneaky.