Dream About Exams And Dangerous Challenges

At first it was a strange school exam hall and there was something I wasn't very good at so I hadn't started/done the paper yet. Someone else did it for me, using Her non-dominant hand to write instead. Then I was on the downstairs toilet at-home trying to pee. People kept opening the door and it was busy. They thought it was funny. I would lock the door and they would unlock it to open it again. The final section was in a university lecture hall. Some kind of final exam where the students would be killed if they failed. Everyone was grouped into colours and that entire colour group would die. A group of guys gave up because they couldn't do the physical challenge then we found out everyone from that colour was at risk of being selected to die, including the family members watching. I was racing down stairs when they failed and almost fell into a grinder because the staircase was moving, it was pulling people into the grinder. Other people not that colour fell into it but it didn't count as a fail and the exam continued.