My buddy, mixing monitors, and I, mixing house, for an entertainer at major casino in Reno were pretty new to the casino scene.  This was back in the mid 70's. Two shows a night, one and two week stands, no night off.  We were walking Reno the second day into the gig and decided to buy new electronic analog watches.  Ametron watches.(I'll never forget the manufacturer.) Nice looking watches, not expensive, not cheap and digital watches were not that great back then.  Three or four or five show days later (not sure) we both got a call in our rooms from the stage manager that the show had started and where were we???  The backline guy was on the monitor board and the house guy was at FOH and we were not there.  Amazingly, both watches had stopped just before the shows.  I know that this sound pretty fishy but it's true.  No major repercussions, a lot of "Oh yeah, sure"s. and some "How the hell could that happen to both watches at the same time?" from us.  Something you never forget.