This is the talk that I'm most proud to have been involved in. Joe Jevnik and I were looking for a way to give a presentation about codetransformer, a Python bytecode manipulation library that we co-maintain. We both wanted to give the talk, but neither of us wanted to do the usual boring format of "you talk for five minutes, then I talk for five minutes".
We eventually hit on the idea of telling the audience that Joe and Scott couldn't make it, and that I was a conference organizer trying to give the talk in their place. The rest of the talk fell into place quickly after that that, and the final result was a unique presentation that still gets me recognized occasionally at conferences.