Noooo, you can't do that!! Please don't ever even try it! I mean, I agree it would be an awesome and hilarious thing to do, and food-stealing pigs deserve it, but you could actually get arrested for that. It's considered poisoning, and people have gotten in very serious trouble for doing it. (YES, even though it's your food and they stole it. You brought it and left it out to entrap them. You deliberately poisoned them. You can and very possibly will be prosecuted. It is a big deal.)  Now, if you knew they were allergic to something, and you made yourself something with that ingredient, that could work, as long as you can convincingly lie that you brought it for yourself and not to entice them into stealing it and having a reaction, and that you didn't know about their allergy. You might get away with that one. Might. But no police offer, judge, or jury is going to believe that you honestly planned to eat a laxative-laced cupcake yourself, so you could get in very serious trouble for that one. No fat is worth that kind of trouble. I'm not posting this to specifically disagree with you, it's more of a public-service message for anyone who might be reading this and considering that as a course of action. Please don't. You could find yourself out of a job and in real legal trouble.