I'm going to move my coworker's food.
What makes you think that it is okay to mess with their food?
She is so annoying and I'm fed up with her.
You need to respect other people's property, especially food. If you are that annoyed with her, why not call HR or have a personal conversation with her about how you feel? There is no need to play immature games like moving other people's food.
Whatever, just call me a psycho.
You are not a psycho, but I do think that you are crossing the line. It is expected that you respect other people's property, even if it is just their food.