Yeah they don’t specify every parameter of human interaction in writing before you have a meeting. I’m not saying that it’s easy, but it’s just one of the challenges of dealing with people. Best of luck with future interviews though. The whole way we hire people in the corporate world has this crazy song and dance to it, but IMO it’s better to learn it a bit. Try not to let it influence your style so much that you’re not telling the company about yourself at all, but learning what kinds of answers the company is looking for can make it much easier to know what the heck to talk about when asked these weird questions.
Putting something full of dangerous bacteria in the water supply isn’t just a prank. If someone put some food safe additive in there to make the water taste or smell bad it’d be less of an issue. (Still a jerk move, debatably.)