You try to ignore it, but somehow it's just impossible.
Picture the following scene: You're in the grocery store, walking down the tasty treats aisle and thinking about picking up some Double Stuf Oreos. You normally don't indulge, but they are on sale for $2 instead of the usual $4. Seriously. Who pays $4 for Oreos? I mean sure, they're "double stuf" but the extra filling can't cost Nabisco that much, can it?
Woah, off track there. So you're looking the Oreos and wondering if the deliciousness is worth walking around with black cookie chunks between every single goddamn tooth in your mouth all day, when a shopping cart turns the corner about twenty feet from you.
