The 5-second rule: how dirty is your food really?

The other day, I stumbled groggily out of bed and went straight to the kitchen, my stomach rumbling uncharacteristically. I reached for some toast, popped it in the toaster, and as I was buttering it I knocked one slice clumsily to the ground. What do I do, I thought. One slice isn't enough, and I'm in a hurry. Should I eat it? The five-second rule says that it's okay. Or is it the three-second rule. My stomach quieted my subconcsious and I guiltily scarfed it down, only after frantically scrapping off the top with a knife, mind you.

But as I went about my day, I couldn't help wondering .... was that a good idea? Is the five-second rule true? According to this, something left of the floor for mere seconds will have significantly less bacteria than something left for a full minute, but that's not saying it's safe to eat food off the floor -- it can still pick up an alarming amount of gross stuff. I think it depends on the texture --- something moist is more likely to pick up bacteria than, say, a cracker. So eating my (buttered) toast probably wasn't a good idea but I did it anyway and seem to have eluded the illness-inducing bacteria. I won't do it again though. Just thinking about it is making me a bit queasy.