[Blaaguuu]

This happens occasionally at my work, and I'm pretty sure it is always accidental - but it is because we get food delivered every day, and a combination of food not being very well labeled, orders getting messed up, and people forgetting what they ordered that day - things get mixed up.

That said, I really can't imagine any situation where it is reasonable if you are talking about people's homemade lunches, in a well labeled lunch box - as is the case in this story.