It was in student halls, not at work, but a few years back I was sharing a fridge with some disgusting individuals that seemed to think that fridges were magical and could keep something fresh forever.
One of them once left a pizza box on the shelf for almost a month. I was desperately trying to avoid getting into the habit of cleaning up after them, but eventually I could take it no more. The box took up an entire shelf, and the contents were blue, furry, and honestly looked like they were a day from getting up and walking off. I threw the box and its contents away, but as it was a large pizza box, it stayed near the top of the bin.
Not even an hour later, Slob demands to know who had thrown away his food. I informed him it wasn't food anymore and hadn't been for several weeks now, but he insisted it was still good and he had intended to eat it "any day now".
So I got a bit mean. I went to the bin, pulled out the box, put it in front of him and told him if he wanted the argument to continue, he had to take a bite of the pizza, right there, right then, in front of the gathered hallmates.
He went slightly green and conceded the point.