I'm generally very nice to telemarketers, mostly because that's a rough job, and I feel bad for them. I hear them out, but then firmly and politely decline. Most of the time, it takes an extra 20 seconds out of my day, but I don't feel like a jerk.
The only time I've ever lost my temper on the phone was with a debt collector. She was from an Ohio company that was calling me about a debt they said I had incurred in Ohio and hadn't paid. At that point, I hadn't lived in Ohio for almost a decade. She asked me to give them my social security number to confirm my identity, which, of course, I refused to do. They refused to tell me what the debt was for unless I would provide my SS#. I insisted that I hadn't lived in Ohio in a long time and had no idea what the debt could be, and I was suspicious of fraud, so I wasn't going to give them my SS#. We went around and around for about 20 mins before I started swearing at her and threw the phone across the room. I can't think of any time in my life I've been angrier--the person on the other end was so painfully stupid and didn't see the apparent problem with what she was proposing.
Why are you calling me, my daddy pays my bill?