I like the idea of putting the dinners into plain brown bags and stapling them shut. Hooooo....just had a GREAT idea, but this will take a little bit of planning.
Take all the dinners out of their cardboard boxes, maybe putting the instructions inside the bags.
Put them *all* into brown paper bags, stapling the bags shut.
Take one of those empty boxes, put the empty box in the bag *BUT*
Put some ice cubes or water, something that will have the weight of a 'dinner' into the plastic tub from a previous dinner...
See where I'm going with this?
You're setting up a decoy but put the decoy on top of your brown-bagged dinners. Maybe even put the decoy into a reallllllly-nice Lean Cuisine box...
So Little Miss Food-Thief will get a box, think it's something wonderful and will get instead?...
a tub of frozen water.
That way, you're not poisoning the person by giving them laxative-filled brownies or something similar, you're just giving the thief some warm/hot water (if they think frozen water resemble a Lean Cuisine). Maybe even put a note in the box saying something like "If you really needed it I would have given you a lunch or dinner if you had asked, instead you had to *steal* it from me."
agnes!