Banned because before you get cake, we must do SCIENCE!
The cake is at the end of the test chambers.
Multiple test subjects err, I mean participants will be doing the same tests and will all end up in the same room with the cake.
However, there is only one cake, so only the first to arrive will get the cake.
Unless he decides to share, which is perfectly acceptable.
The cake also contains the antidote for the specific Deadly Neurotoxin I've been flooding your rooms with.
You have to eat the entire cake to get a big enough dosage of the antidote for it to have any effect.
The test will start in...
3...
2...
1...
[door opens]