When my mother and I were on a coach tour in Europe, our group was "treated" to a meal at an Italian restaurant to make up for some shabby rooms that we'd been asked to stay in. Anyway, all of a sudden one of the fellows in the tour group stood up with his wife and left the restaurant and they were followed by everyone at their table. Turned out the man had bitten into a piece of chewing gum that had been in his salad...

And my brother, when he was in Year 7 and doing cooking at school, made some rissole and rice dish but had dropped it, scooped everything up and put it into another container and didn't tell us. Twigged when we found some shards of glass...