This happened over ten years ago, but it still rubs me the wrong way when I think about it. I was in college, and two days in a row my car had refused to start. I took it to a car place. (Possibly Advance Auto Parts? I forget.) Anyway, I went to talk to one of the employees, and I told him my car hadn't started twice. I said I thought my battery was dead. He had a very slightly amused look on his face, and when he spoke his tone was very patronizing. I don't remember his exact words, but it was something like, "It's probably not your battery. There's a lot of reasons your car might not start, but we'll test the battery just in case." If he had said that in a normal tone, I'd have been fine. I admit, I don't know much about cars. But the patronizing tone really grated on me. To top everything off, after he tested my battery he came back to me and said, "Well, it looks like your battery is dead. You're going to need a new one." If this happened now I'd probably say something snarky along the lines of, "Gee, I never would have guessed!" Back then though I was a lot shyer so I just nodded and let them install a new battery. It still annoys me.