Not sure what those three people did right. It sounds like, however, that it COULD have been contamination of the food. One or two of the people who lived in that house, had been sick Thursday and Friday. With the party on Saturday, maybe they were still contagious and contaminated the food they were making. Not sure. I talked to someone who had NOT gotten sick and she said she ate the same things her husband ate, and he got insanely sick while she didn't. Weirdness....You never know sometimes exactly how it happens....