That was the question asked by one of my girlfriends housemates. His part of the fridge is regulary home to ancient ready-meals or 'frozen food' which has been sitting there for weeks having long since defrosted. There is even a home made stir fry which he brought back in the new year. Still there. Untouched. Probably home to billions of partying bacteria.
A brief check in his cupboard revealed some very blue and mouldy muffins. Before that, there was some nice and mouldy fruit. We're all surprised that he hasn't managed to give himself food poisoning yet.
We all thought his cavalier attitude to old food was because he never bothered checking dates. It turned out that he didn't realise that you shouldn't eat food which has gone beyond it's best-before date, that it might possibly be bad for you.