I live in an apartment with roommates, I'm trying to determine who is stealing my food. I use the word stealing because each of us had have our own separate and color-coded cabinets, and I also label all my food.
For a situation like this, what does halacha say about the permissibility of "poisoning" one's own food in a way that produces a noticable effect without doing harm? The goal is to identify the thief by seeing who, say, breaks out into a sneezing fit.
(For practical advice, of course consult your own rabbi.)