Having just composted the last of some funky-tasting cottage cheese and sour cream with a layer of faint pink gel on top--I didn't taste that one--I was interested to learn what WCCO's Good Question reporter Jason DeRusha recently discovered about expiration dates.
According to the food science prof he talked to, the dates aren't necessarily scientifically based, and often are simply esitmates of when the food will start to lose its taste, not when they might become unsafe. Bottled water--which you shouldn't be drinking anyway--often has a two-year shelf life, for example, but water will never degrade unless it's stored in sunlight and the plastic won't start to break down for about a decade. As for expiration dates on drugs like Aspirin or Tylenol, the dates are an estimate of when the active ingredient will lose 10 percent of its effectiveness, so you can pop a couple from 2002 without harm.
I remember my friend's parents used to have a bottle of O'Doul's that had been in their fridge for at least a decade (it may still be there...)--I don't think my kitchen contains anything that could top that. Do you regularly eat expired items and worry that you're taking your life in your hands?