I once worked at a water park, for an entire month, as a teen. They would send weighted 'bodies' down the river to see if we rescued them. One time, they said they sent one and I missed it (and, boy, I must have really missed it cause I saw no such thing). At the time, I thought they were being a-holes testing me when there's no real danger. Looking back, I'm glad they tested us and I'm equally glad I stopped working there. You don't want that type of thing on your conscience.