Is there some medicine that can safely and reliably cause mild nausea? Like a pill that would make the one who takes it nauseous for an hour and that's it. And by safely I mean that there would not be any other adverse effects except the nausea itself.
Sounds like you have a test to avoid, in which case you can probably just say you are feeling nauseous. If you really want to make yourself (or someone else) feel nauseous, depending on your sensitivity to motion sickness, you can put wamr (or cold) water in the ear canal. This is basically what a caloric test of balance is.