Maybe it’s a crime IIRL, but in the privacy of one’s imagination, one can dream …
I take it you haven’t read all the provisions of the Patriot Act.
I had a coworker walk into the office from the kitchen one time with the most disgusted look on her face, she said someone had taken her sandwich. I shrugged, not too surprised, and she said, “but I took a bite out of it on my way to work.” Ewwww!
Are you allowed to create something really disgusting, though? Like someone suggested a catfood sandwich once. Not poison, just some really gross combination. (Peanut butter, spam and italian dressing, maybe?)
I believe it was 8 or 9 years ago someone on this board was having trouble with their lunch disappearing from the fridge at work. One day they made their sandwich, cleaned their hairbrush, placed the results in the middle of the sandwich, and then placed it in the fridge as usual. If memory serves me, that was the last day their lunch was taken.
Quite.
OTOH, Aunt Emma’s Famous Prune Brownies are completely fine.
We have a communal snack bar area with fridge. The hardware department goes to Sams Club once a month to load up on soda and snacks for the whole building mainly for convenience but also to save a few bucks for everybody, so it’s .50 for soda and .50 or .75 for various snacks.
It has been on the honor system for years and has mostly worked well but it only takes one person to mess it up for everyone. The amount was beginning to not add up each month. At first maybe 2 dollars low a month but it gradually grew into around 15 dollars or more per month.
My boss finally got fed up and installed a web cam to catch the person(s). It turned out to be a programmer in the systems department who’s salary was 50,000+ per year.
What the hell? I guess some people just do it for the thrill.
Thoughtcrime is not a thing that can be concealed forever. You might dodge successfully for a while, even for years, but sooner or later they are bound to get you.
Or because they’re entitled shits.
I’m going with “entitled shits,” personally.
Silvorange, it sounds like your office is infested. I would council against setting out poison bait such as ex-lax brownies. Though effective, the vermin will hide in a location away from the site of the poison. After the poison has done its job, the only way to find the animal is by locating the source of the bad smell. It can take weeks to get that stench out.
It’s best just to go the old fashioned way and use mechanical traps. It’s a bit bloody, though, so use gloves and a trash bag during the clean up. Some people are hesitant to use these, but I’ve found them to be the most effective and hassle free method.
In regards to the ex-lax brownies, could you just use the “Who stole my specially medicated diet brownie?!” defense?
I don’t really support the idea that you should get in trouble if you tamper with some food and someone steals and eats it (and gets sick). A good way to avoid getting sick from eating other people’s tampered food is to (wait for it) not steal other people’s food.
On one level it certainly seems rather unfair, but on another level it’s probably a good idea. IANAL, but AFAIK you do incur liability for booby-trapping your own property. Just as you can’t put a bear trap in your car or your house to injure a burglar, you can’t put poisons or drugs in your food to deliberately injure a food thief.
Or at least, if you do and the thief gets pissy about it, they may very well be able not only to sue you but bring charges against you, depending on how dangerous your booby-trap was.
As I said, this is probably a good idea on the whole, just to decrease the likelihood of horrific unintended consequences. Imagine how you’d feel if you put some OTC medication in your sandwich to punish your lunch-pilfering coworker, and it was found and eaten by another coworker’s pre-schooler who had to be rushed to the ER for a stomach-pumping, or worse.
However, AFAIK there’s no liability for making your food merely revolting rather than actually poisoned or contaminated. Feeling in the mood for a yummy kimchi and canned frosting sandwich? 
Well, no. Nobody would believe that.
What they would believe is Mexican chocolate brownies, where Mexican chocolate is chocolate made spicy using cayenne pepper. Frankly, anyone who hasn’t heard of Mexican chocolate is a philistine, and anyone who bites into Mexican chocolate expecting something more along the lines of Hershey’s is in for a shock regardless of whether they can stand the heat.
Finally, I can stand the heat. I can stand it well into the Tabasco/Sriracha range of spices. I also happen to honestly enjoy spicy Mexican chocolate and there are witnesses to that effect.
I don’t really support the idea that you can’t put a bear trap in your house or car to injure a burglar, either. Maybe not a bear trap; maybe just a nice rat trap or something. 
How is the person who ate the poisoned food going to know it was yours in the first place? Unless you use a distinctive Toy Story lunchbox and talk about it all the time. Put the crap in a plain brown (or plastic) bag.
Do it.
rachelellogram, while the Straight Dope does permit the discussion of illegal subjects, we do forbid the promotion of illegal acts. It is, admittedly, a pretty fine line, but I feel that you’ve ended up on the wrong side of it with this post. No warning issued, but please do not encourage other posters to break the law, or give them advice on how to get away with it.
-Peanut butter, mustard and paprika, with crushed up Altoids? Ketchup and nutella with Limberger cheese?
Could you find some sick kid and have him lick your sandwich and deposit some of his germs or would that be considered Germ Warfare?
Well, same deal: seems like perfectly good retributive justice in theory, but in practice A Lot Can Go Wrong.
That would be less grisly [snerk], but still not immune from the horrific unintended consequences thing.
All in all, while I sympathize with the desire to give housebreakers and lunch-pilferers their comeuppance, I think it’s probably a safer world for all of us if setting traps for them remains illegal.
Irrespective of the legality of the biohazard thing, how would your lunch-pilfering coworker ever figure out that eating your sandwich was why he came down a few days later with that bug that’s been going around?
It ain’t really punishment unless the wrongdoer knows he’s being punished, is it?
Now that ketchup/nutella/limburger sandwich, on the other hand, will make the retribution clear at first bite.