Have several (though different things).
- Someone (who shall remain nameless) threw something at a wall and it just so happened to hit the big red power off button on the wall. Cue the clunk as all the power went off. Totally unintended (but an impressive shot none-the-less).
- An engineer who was working on a removable disk drive (ICL, platters almost the size of Morris Minor's wheel hub) wondered why the drive motor had tripped. Pushed the button, the rather large capacitor on the side of the drive blew up. Very impressive mini mushroom cloud too - right under the smoke detector!
- Funniest one was a manager hitting the big red button on the aircon unit (this thing was BIG, at the back of the building with one or two massive fans and it blew air into the machine room). Then he couldn't work out how to re-engage it (there was a lock ring that had to be twisted to release the button).
I miss those days....