Lunch theft is a serious problem in some offices. You go through all the trouble of shopping, cooking, and then hauling it al the way to work, only to find yourself hungry, angry, and without a plan. Well heres the plan for next week: anti-theft lunch bags, available here.
Alternatively, you could just sprinkle a bit of spirulina powder on the bread. This will make it more healthy and give you the same effect.
If all else fails, this Ghost Pepper Naga Jolokia is one of the hottest hot sauces out there. Add a very liberal dose to a decoy lunch, and then go out to eat, secure in the knowledge that while you are enjoying your lunch, some thief is getting a preview of their afterlife.