It all depends on what the food is...and what you mean by "stale".
Stale bread makes excellent croutons. (You cube it, saute the cubes in a little oil and seasonings like garlic, soy sauce until they're crispy and there you go.) Put them in salad (like a Caesar salad) or soup. Yummy!
If there's anything gray-greenish, hairy and/ or moldy growing on your food (except, possibly, cheese which is aged with various molds), then I'd pass (put it in the trash or in your compost heap).
If you mean foods that are past their "sell-by date", there's usually a bit of leeway, and some foods keep longer than others, like yogurt, for instance.
However, when in doubt, throw it out.
It's not worth making yourself sick!
