I only once saw John Conway giving a talk. I don't remember the topic (it was >20y ago), but I remember how it went. He gave some definitions, then started to give some examples and work out on the blackboard some calculations. It all felt quite trivial. At some point one calculation doesn't work out. He checked again, but still it didn't work. He started pacing in front of the blackboard, and said that this is quite embarrassing. "Hm, I wanted to give a talk about this, but since we found this mistakes, I'm not sure what to say for the remaining 50 minutes". Ok, he said, let's take a step back and start again. And he started again, and the talk was amazing. The whole "embarrassing" thing had been staged. He played a bit of misdirection on us. He started with something that seemed quite trivial, pretended to make a mistake, then showed us how much deeper the topic was.

This was not the only math talk I've seen that was actually a performance, but it was the best.

Rest in peace.