I used to do that - pick names that were similar or the same, then conference them together. I had a 2-line phone, so I would use my line and my parents line to dial them at the exact same time. I'd also hook up Chinese restaurants together and listen to them rant at each other in Chinese. Or I'd hook up competing businesses, rival BBSers, kids from my school. Kids from my school were the best - I'd pick 2 people that would never normally talk to each other. Sometimes they would skip the whole, "You called me. No, you called ME!" and would just talk to each other. I wonder if I created any lasting friendships that way.
I love the idea of calling an old person and making them talk to their self. I really need to try that.