I’ve seen that happen a couple of times. I know there was an infamous Microsoft one, where the demo BSOD’d on Bill Gates (Not WWDC. I wasn’t there, but I’m sure there’s video). Microsoft used to demo real unstable stuff.

I remember one WWDC, where Ian Diery was giving a demo with a young man, and asked “Where’s the beef?” The kid looked down at his pants, and the crowd burst into laughter.

Diery did not laugh. He was a fairly serious chap, with no discernible sense of humor, so I expect his assistant was sanctioned for that.

I think the last DuDub I went to, was around 2005 (pre-iPhone). I know it was at Moscone. Jobs led that. He was one of the best presenters I’ve ever seen. He could recover from curveballs almost imperceptibly.

The first, was in 1987, or 1988. One of the first.