I use the same container as a coworker. His wife packs his lunch. When I bring in chili or spaghetti he could honestly mistake it for his own. Less likely with most of my lunches though.

And that’s not a hypothetical. He hasn’t confused our lunches but we do use the same style Pyrex containers. Mine is usually in a bag with fruit and such, but occasionally I put it in the fridge by itself.

At our office, nobody brings lunch boxes. Our office manager is always ordering snacks for the fridge, and there's leftovers from group lunches.

It would be easy for someone to think some food was leftover from the day before, or that an apple or yogurt was meant for anyone.

It might be precariously positioned, and an unwitting coworker might have the misfortune of opening the refrigerator door only to see your pyrex lunch container fall to the ground and shatter. They clean it up, but are in too much of a rush to make a company-wide announcement of the smashed lunch.

You come back to a missing lunch and become incensed, but start to cool off when given an explanation.

Here's mine: https://news.ycombinator.com/item?id=16959947

Oh! and another: We have a certain corner table in our lunch room where we traditionally put free food. Someone set their lunch item there while doing something else. I grabbed it and ate it. When we realized I apologized profusely(while other co-workers said "oops, she shouldn't have put it there"), then bought her a replacement.

Someone else reshuffles the boxes in the fridge to make space?

Also, especially in tech workplaces, never underestimate absentmindedness.