So...
I was on a panel at Phoenix Fan Fusion (Previously Phoenix Comic Fest, but never to be referred to as Phoenix Comicon for legal reasons). The panel was called "Marching Orders," and was about writing realistic military sci-fi.
I showed up to the panel about half an hour early- just as the previous panel was letting out. I sat in the audience and waited. The chairs started filling in around me, and when the room was ready, I started making up stuff about all the panelists. At first, it was plausible- "Did you know that Melinda Snodgrass wrote the entire third season of ST:TNG?" (She only wrote "Measure of a Man.) Then, I ramped it up: "Did you know that Sylvain Neuvel and Fabio were competitors in Milan?" Then I went to bizarre world: "Did you know that Old Man's War is an autobiography, and that John Scalzi is a time-traveling Space Marine?"
By this time, the room is full, and the panel is supposed to start. Kevin Ikenberry is like, "Where's Gardner?" John Scalzi surveys the crown and points me out. "He's in the audience." The entire panel audience simultaneously turns to look at me, so I wave and run up to the stage. At the Q&A stage, a congoer asks, "Mark Gardner said that when Scalzi appeared for this panel, he would rise from the stage floor and there would be smoke effects and light effects." Scalzi turns to him without missing a beat and replies, "And that's exactly what happened. Don't let anyone tell you otherwise."